"""Simulation plan API router (CRUD + download + upload results + start simulation)."""
import json
import math
import uuid
from datetime import datetime
from fastapi import APIRouter, Depends, HTTPException, UploadFile, File
from sqlalchemy.orm import Session

from ..database import get_db
from ..metrics_constants import METRIC_KEYS
from ..models.project import Project
from ..models.simulation_plan import SimulationPlan
from ..models.simulation_result import SimulationResult
from ..schemas.simulation_plan import (
    PlanCreate, PlanUpdate, PlanResponse, PlanListResponse, PlanDownloadResponse,
)
from ..schemas.simulation_result import ResultListResponse
from ..services.task_manager import get_task_manager

router = APIRouter(prefix="/api/plans", tags=["plans"])

@router.get("/variable-catalog")
def get_variable_catalog(topology: str = "SSSR"):
    """Return topology-aware variable catalog for frontend scan-variable selectors.

    Returns the fixed-parameter template (with motorcad_var resolved) and
    the set of known Motor-CAD variable names for the given topology.
    Frontend should use this to populate scan-variable dropdowns and prevent
    users from entering invalid variable names.

    Args:
        topology: Motor topology (SSSR/AFIR/RFM). Defaults to SSSR.
    """
    from ..services.fixed_params_template import FIXED_PARAM_TEMPLATES
    from ..services.topology_variable_map import (
        get_known_variables,
        normalize_topology,
        resolve_variable,
    )

    topo = normalize_topology(topology)

    # Build template with resolved motorcad_var for this topology.
    # For params where motorcad_var is None but the name is a known alias,
    # resolve it. Otherwise keep name as the variable name if known.
    template = []
    for p in FIXED_PARAM_TEMPLATES:
        row = dict(p)
        mc_var = row.get("motorcad_var")
        if not mc_var:
            # Try to resolve from alias map
            resolved, was_alias = resolve_variable(row["name"], topo)
            if was_alias:
                row["motorcad_var"] = resolved
            else:
                row["motorcad_var"] = row["name"]
        template.append(row)

    known_vars = sorted(get_known_variables(topo))

    return {
        "topology": topo,
        "template": template,
        "known_variables": known_vars,
        "total_known": len(known_vars),
        "total_template": len(template),
    }


def _generate_plan_id() -> str:
    """Generate a unique plan ID with timestamp + random suffix to avoid collisions."""
    return f"SP-{datetime.now().strftime('%Y%m%d-%H%M%S')}-{uuid.uuid4().hex[:6]}"


def _plan_to_response(db: Session, plan: SimulationPlan) -> PlanResponse:
    result_count = db.query(SimulationResult).filter(SimulationResult.plan_id == plan.id).count()
    variables_summary = {}
    try:
        variables_summary = json.loads(plan.variables_summary) if plan.variables_summary else {}
    except (json.JSONDecodeError, TypeError):
        pass
    return PlanResponse(
        id=plan.id,
        project_id=plan.project_id,
        name=plan.name,
        plan_id=plan.plan_id,
        status=plan.status,
        plan_data=plan.get_plan_dict(),
        variables_summary=variables_summary,
        estimated_points=plan.estimated_points or 0,
        estimated_time_min=plan.estimated_time_min or 0,
        notes=plan.notes or "",
        result_count=result_count,
        created_at=plan.created_at,
        updated_at=plan.updated_at,
    )


@router.get("", response_model=PlanListResponse)
def list_plans(
    project_id: int | None = None,
    skip: int = 0,
    limit: int = 50,
    db: Session = Depends(get_db),
):
    """List simulation plans, optionally filtered by project."""
    query = db.query(SimulationPlan)
    if project_id:
        query = query.filter(SimulationPlan.project_id == project_id)
    total = query.count()
    plans = query.order_by(SimulationPlan.updated_at.desc()).offset(skip).limit(limit).all()
    return PlanListResponse(total=total, items=[_plan_to_response(db, p) for p in plans])


@router.post("", response_model=PlanResponse, status_code=201)
def create_plan(data: PlanCreate, db: Session = Depends(get_db)):
    """Create a new simulation plan."""
    project = db.query(Project).filter(Project.id == data.project_id).first()
    if not project:
        raise HTTPException(status_code=404, detail="Project not found")

    plan_id = _generate_plan_id()
    plan_data = data.plan_data
    plan_data["plan_id"] = plan_id

    # Persist the project boundary conditions (normalized to canonical BC
    # keys) when the caller did not supply them, so the plan-detail boundary
    # display has data and the plan is traceable to its BC (P1-1).
    if not plan_data.get("boundary_conditions"):
        from ..services.bc_fields import normalize_bc
        plan_data["boundary_conditions"] = normalize_bc(project.get_boundary_conditions())
    # Source tracking: manually created plans inherit all BC from the project
    # (user-specified). AI-generated plans tag sources in ai_plan.py instead.
    if not plan_data.get("bc_meta"):
        plan_data["bc_meta"] = {
            k: {"source": "user"} for k in (plan_data.get("boundary_conditions") or {})
        }

    # Auto-fill the base model from the topology registry when neither the
    # caller nor the project provided a model path.
    if not (plan_data.get("model_path") or "").strip():
        from src.afmcore.topology import default_model_for
        fallback = default_model_for(plan_data.get("topology") or project.topology or "")
        if fallback:
            plan_data["model_path"] = fallback

    # Validate against the single-source plan schema (draft-stage: model
    # path may be configured later).
    from src.plan_schema import validate_plan_dict
    _ok, _errs = validate_plan_dict(plan_data, require_model_path=False)
    if not _ok:
        raise HTTPException(
            status_code=400,
            detail="Invalid plan_data: " + "; ".join(_errs),
        )

    # Extract variables summary for display
    variables_summary = {}
    estimated_points = 1
    for var in plan_data.get("variables", []):
        name = var.get("name", "unknown")
        values = var.get("values", [])
        variables_summary[name] = {
            "unit": var.get("unit", ""),
            "values": values,
            "count": len(values),
        }
        estimated_points *= len(values) if values else 1

    plan = SimulationPlan(
        project_id=data.project_id,
        name=data.name,
        plan_id=plan_id,
        status="draft",
        estimated_points=estimated_points,
        estimated_time_min=estimated_points * 3,  # ~3 min per point estimate
        notes=data.notes,
    )
    plan.set_plan_dict(plan_data)
    plan.variables_summary = json.dumps(variables_summary, ensure_ascii=False)

    db.add(plan)
    db.commit()
    db.refresh(plan)
    return _plan_to_response(db, plan)


@router.get("/{plan_id}", response_model=PlanResponse)
def get_plan(plan_id: int, db: Session = Depends(get_db)):
    """Get a plan by ID."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    return _plan_to_response(db, plan)


@router.put("/{plan_id}", response_model=PlanResponse)
def update_plan(plan_id: int, data: PlanUpdate, db: Session = Depends(get_db)):
    """Update a plan."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    update_data = data.model_dump(exclude_unset=True)
    if "plan_data" in update_data:
        from src.plan_schema import validate_plan_dict
        _ok, _errs = validate_plan_dict(
            update_data["plan_data"], require_model_path=False
        )
        if not _ok:
            raise HTTPException(
                status_code=400,
                detail="Invalid plan_data: " + "; ".join(_errs),
            )
        plan.set_plan_dict(update_data.pop("plan_data"))
    for key, value in update_data.items():
        setattr(plan, key, value)
    db.commit()
    db.refresh(plan)
    return _plan_to_response(db, plan)


@router.delete("/{plan_id}", status_code=204)
def delete_plan(plan_id: int, db: Session = Depends(get_db)):
    """Delete a plan and its results."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    db.delete(plan)
    db.commit()
    return None


# ---------------------------------------------------------------------------
# API integration endpoints (for local executor)
# ---------------------------------------------------------------------------

@router.get("/{plan_id}/download", response_model=PlanDownloadResponse)
def download_plan(plan_id: int, db: Session = Depends(get_db)):
    """Download a plan as simulation_plan.json (read-only, F5 fix).

    This is the API endpoint used by the local execution system to fetch plans.
    Returns the raw plan JSON in the exact format expected by src/plan_schema.py.
    Status changes must go through POST /{plan_id}/start-execution.
    """
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    return PlanDownloadResponse(plan_id=plan.plan_id, plan_data=plan.get_plan_dict())


@router.post("/{plan_id}/start-execution")
def start_execution(plan_id: int, db: Session = Depends(get_db)):
    """Mark a plan as executing (explicit state transition, F5 fix)."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    if plan.status in ("draft", "confirmed"):
        plan.status = "executing"
        db.commit()
    return {"plan_id": plan.plan_id, "status": plan.status}


@router.get("/by-plan-id/{plan_uuid}/download", response_model=PlanDownloadResponse)
def download_plan_by_uuid(plan_uuid: str, db: Session = Depends(get_db)):
    """Download a plan by its plan_id string (read-only, F5 fix)."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.plan_id == plan_uuid).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    return PlanDownloadResponse(plan_id=plan.plan_id, plan_data=plan.get_plan_dict())


@router.post("/{plan_id}/upload-results", status_code=201)
async def upload_results(
    plan_id: int,
    file: UploadFile = File(...),
    db: Session = Depends(get_db),
):
    """Upload scan_results.csv from local executor.

    Parses the CSV and stores each row as a SimulationResult.
    This is the API endpoint used by the local execution system to push results back.
    """
    import csv
    import io

    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")

    # Clear existing results for this plan (re-upload replaces)
    db.query(SimulationResult).filter(SimulationResult.plan_id == plan_id).delete()

    content = await file.read()
    text = content.decode("utf-8-sig")
    reader = csv.DictReader(io.StringIO(text))

    # A1 fix: use shared metric constants (single source of truth)
    metric_keys = METRIC_KEYS
    standard_keys = {"run_index", "status", "seconds", "error"}

    count = 0
    for row in reader:
        params = {}
        metrics = {}
        for key, val in row.items():
            if key in standard_keys or val == "" or val is None:
                continue
            try:
                fval = float(val)
            except (ValueError, TypeError):
                continue
            if key in metric_keys:
                metrics[key] = fval
            else:
                params[key] = fval

        result = SimulationResult(
            plan_id=plan_id,
            run_index=int(row.get("run_index", count + 1)),
            status=row.get("status", "OK"),
            solve_time_s=float(row.get("seconds", 0) or 0),
            error_message=row.get("error", ""),
        )
        result.set_params(params)
        result.set_metrics(metrics)
        db.add(result)
        count += 1

    # Update plan status
    plan.status = "completed"
    db.commit()

    return {"message": f"Uploaded {count} results", "count": count, "plan_id": plan.plan_id}


@router.get("/{plan_id}/results", response_model=ResultListResponse)
def get_plan_results(plan_id: int, db: Session = Depends(get_db)):
    """Get all results for a plan."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    results = (
        db.query(SimulationResult)
        .filter(SimulationResult.plan_id == plan_id)
        .order_by(SimulationResult.run_index.asc())
        .all()
    )
    from ..schemas.simulation_result import ResultResponse
    items = [
        ResultResponse(
            id=r.id, plan_id=r.plan_id, run_index=r.run_index,
            status=r.status, solve_time_s=r.solve_time_s,
            params=r.get_params(), metrics=r.get_metrics(),
            error_message=r.error_message or "", created_at=r.created_at,
        )
        for r in results
    ]
    return ResultListResponse(total=len(items), items=items)


# ---------------------------------------------------------------------------
# One-click simulation start (P0-4)
# ---------------------------------------------------------------------------


def _expand_plan_to_parameters(plan_data: dict) -> list[dict]:
    """Expand plan variables into full parameter sets (Cartesian product).

    Fixed params are canonicalized against the template: the template is the
    source of truth for the real Motor-CAD variable name (motorcad_var),
    while the plan's stored value overrides the template default. Only params
    with a real motorcad_var are written to the simulation.

    Scan variables are resolved through:
    1. The template (if name matches a template param, use its motorcad_var)
    2. The topology-aware alias map (RFM names remapped to AFM names)
    3. Fallback: use the name as-is (caller should validate).

    Returns list of param dicts for the task executor.
    """
    from ..services.fixed_params_template import FIXED_PARAM_TEMPLATES
    from ..services.topology_variable_map import (
        resolve_variable,
        normalize_topology,
    )

    topology = normalize_topology(plan_data.get("topology"))
    template_by_name = {p["name"].lower(): p for p in FIXED_PARAM_TEMPLATES}

    plan_fps = plan_data.get("fixed_params", []) or []
    seen = set()
    merged = []
    for fp in plan_fps:
        if not (isinstance(fp, dict) and fp.get("name")):
            continue
        name = fp["name"]
        key = name.lower()
        if key in seen:
            continue
        seen.add(key)
        tmpl = template_by_name.get(key)
        val = fp.get("value")
        if tmpl:
            row = dict(tmpl)  # includes motorcad_var (baseline-tuned default)
            # Only user-explicitly-modified values override the baseline
            # default. AI-suggested values (or legacy params without source)
            # keep the template default so old plans run with valid geometry.
            if fp.get("source") == "user" and val is not None and val != "":
                row["value"] = val
            merged.append(row)
        else:
            # Param not in template: try topology alias resolution.
            # If the alias map resolves it, use the resolved name as
            # motorcad_var. Otherwise keep None (will not be written).
            row = dict(fp)
            resolved, was_alias = resolve_variable(name, topology)
            if was_alias:
                row["motorcad_var"] = resolved
            else:
                row["motorcad_var"] = None
            merged.append(row)
    # Template params missing from the plan (fill with template defaults)
    for tmpl in FIXED_PARAM_TEMPLATES:
        if tmpl["name"].lower() not in seen:
            merged.append(dict(tmpl))
            seen.add(tmpl["name"].lower())

    fixed = {}
    for fp in merged:
        var = fp.get("motorcad_var")
        val = fp.get("value")
        if var and val is not None and val != "":
            try:
                fixed[var] = float(val)
            except (TypeError, ValueError):
                fixed[var] = val

    variables = plan_data.get("variables", [])
    if not variables:
        return [dict(fixed)]

    # Collect value lists for each variable, resolving the variable name
    # through template -> topology alias map -> fallback to raw name.
    var_value_lists = []
    for v in variables:
        if not isinstance(v, dict):
            continue
        name = v.get("name", "")
        if not name:
            continue
        # Resolve the Motor-CAD variable name for this scan variable.
        tmpl = template_by_name.get(name.lower())
        if tmpl and tmpl.get("motorcad_var"):
            resolved_name = tmpl["motorcad_var"]
        else:
            resolved_name, _was_alias = resolve_variable(name, topology)
        values = v.get("values", [])
        if not values and v.get("start") is not None and v.get("stop") is not None and v.get("step"):
            start, stop, step = float(v["start"]), float(v["stop"]), float(v["step"])
            count = int(math.floor((stop - start) / step + 1e-9)) + 1
            values = [round(start + i * step, 6) for i in range(count)]
            if values and abs(values[-1] - stop) > 1e-9:
                values.append(round(stop, 6))
        if values:
            var_value_lists.append((resolved_name, values))

    if not var_value_lists:
        return [dict(fixed)]

    # Cartesian product
    def _cartesian(idx: int, current: dict) -> list[dict]:
        if idx >= len(var_value_lists):
            return [dict(current)]
        name, vals = var_value_lists[idx]
        result = []
        for val in vals:
            current[name] = val
            result.extend(_cartesian(idx + 1, current))
        return result

    return _cartesian(0, dict(fixed))

@router.get("/{plan_id}/preflight")
def preflight_check(plan_id: int, db: Session = Depends(get_db)):
    """Pre-flight checklist before starting a simulation.

    Returns machine-readable checks (key/status/data only; the frontend maps
    keys to localized labels and messages). status: pass | warn | fail.
    Any 'fail' blocks starting; 'warn' is advisory and does not block.
    """
    import os
    from ..config import PROJECT_ROOT
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")
    plan_data = plan.get_plan_dict()
    checks = []

    # 1. Model file must exist. model_path may be repo-relative (e.g.
    # "models/xxx.mot") or absolute; resolve relative paths against the repo
    # root so the check matches how the executor locates the model.
    model_path = (plan_data.get("model_path") or "").strip()
    resolved = model_path
    if model_path and not os.path.isabs(model_path):
        resolved = os.path.join(str(PROJECT_ROOT), model_path)
    # Expose the topology's default base model so the UI can offer one-click
    # repair when the check fails.
    from src.afmcore.topology import default_model_for
    default_model = default_model_for(plan_data.get("topology") or "")
    if not model_path:
        checks.append({
            "key": "model_path", "status": "fail", "value": "",
            "fixable": bool(default_model), "default_model": default_model,
        })
    elif not os.path.exists(resolved):
        checks.append({
            "key": "model_path", "status": "fail", "value": model_path,
            "fixable": bool(default_model), "default_model": default_model,
        })
    else:
        checks.append({"key": "model_path", "status": "pass", "value": model_path})

    # 2. Fixed params whose Motor-CAD variable name is unverified (no mapping).
    unverified = [
        fp["name"] for fp in (plan_data.get("fixed_params") or [])
        if isinstance(fp, dict) and fp.get("name") and not fp.get("motorcad_var")
    ]
    checks.append({
        "key": "unverified_vars",
        "status": "warn" if unverified else "pass",
        "items": unverified,
    })

    # 3. At least one scan variable with values.
    variables = plan_data.get("variables") or []
    valid_vars = [
        v for v in variables
        if isinstance(v, dict) and v.get("name") and (v.get("values") or [])
    ]
    checks.append({
        "key": "scan_vars",
        "status": "pass" if valid_vars else "fail",
        "count": len(valid_vars),
    })

    # 4. Point-count estimate (advisory when large).
    total = 1
    for v in valid_vars:
        total *= len(v.get("values") or [1])
    checks.append({
        "key": "point_count",
        "status": "warn" if total > 200 else "pass",
        "count": total,
    })

    # 5. Local executor online (advisory: tasks can queue while offline).
    try:
        exec_status = get_task_manager().get_executor_status()
        online = sum(1 for e in exec_status.get("executors", []) if e.get("online"))
    except Exception:
        online = 0
    checks.append({
        "key": "executor",
        "status": "pass" if online > 0 else "warn",
        "online": online,
    })

    ok = not any(c["status"] == "fail" for c in checks)
    return {"ok": ok, "checks": checks}


@router.post("/{plan_id}/start-simulation")
def start_simulation(plan_id: int, db: Session = Depends(get_db)):
    """One-click start: expand plan to parameters, create task, dispatch.

    Automatically:
    1. Expands variables into Cartesian product parameter sets
    2. Merges fixed_params into each parameter set
    3. Creates a Task linked to this plan
    4. Marks task as dispatched (local executor picks it up)
    5. Updates plan status to 'executing'

    Returns the created task info.
    """
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")

    plan_data = plan.get_plan_dict()

    # Runtime fallback: legacy plans may carry an empty model_path (created
    # before the topology default-model auto-fill). Auto-fill from the
    # topology registry and persist so the plan becomes self-contained.
    if not (plan_data.get("model_path") or "").strip():
        from src.afmcore.topology import default_model_for
        fallback = default_model_for(plan_data.get("topology") or "")
        if fallback:
            plan_data["model_path"] = fallback
            plan.set_plan_dict(plan_data)
            db.commit()

    parameters = _expand_plan_to_parameters(plan_data)

    if not parameters:
        raise HTTPException(status_code=400, detail="Plan has no valid parameters to simulate")

    # --- Topology-aware variable name validation (P1-bugfix: plan 23) ---
    # Reject unknown variable names BEFORE creating the task, with suggested
    # alternatives. This prevents silent Motor-CAD "Could not find variable"
    # failures that waste 15+ minutes of simulation time.
    from ..services.topology_variable_map import (
        is_known_variable,
        suggest_alternative,
        normalize_topology,
    )
    topo = normalize_topology(plan_data.get("topology"))
    if parameters:
        all_var_names = list(parameters[0].keys())
        unknown = []
        for vname in all_var_names:
            if not is_known_variable(vname, topo):
                suggestion = suggest_alternative(vname, topo)
                unknown.append({
                    "variable": vname,
                    "suggestion": suggestion,
                })
        if unknown:
            detail_lines = [
                f"Unknown Motor-CAD variable(s) for topology {topo}. "
                "These will cause 'Could not find variable' errors in Motor-CAD.",
            ]
            for u in unknown:
                if u["suggestion"]:
                    detail_lines.append(
                        f"  - '{u['variable']}' -> did you mean '{u['suggestion']}'?"
                    )
                else:
                    detail_lines.append(
                        f"  - '{u['variable']}' (no close match found; verify against .mot model)"
                    )
            raise HTTPException(status_code=400, detail="\n".join(detail_lines))
    # --- End variable name validation ---

    # Create task via task manager
    manager = get_task_manager()
    task = manager.create_task(
        plan_id=plan_id,
        plan_data=plan_data,
        parameters=parameters,
        task_name=f"{plan.name}_run",
        priority=5,
        created_by="web",
    )

    # Dispatch immediately
    try:
        manager.dispatch_task(task["task_id"])
    except ValueError:
        pass  # Already dispatched or other state issue

    # Update plan status
    plan.status = "executing"
    db.commit()

    return {
        "task_id": task["task_id"],
        "task_name": task["task_name"],
        "plan_id": plan.plan_id,
        "total_points": len(parameters),
        "status": "dispatched",
        "message": f"Simulation started with {len(parameters)} points. Local executor will pick it up.",
    }


@router.get("/{plan_id}/active-task")
def get_active_task(plan_id: int, db: Session = Depends(get_db)):
    """Get the most recent active task for a plan (for progress display)."""
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")

    manager = get_task_manager()
    tasks = manager.list_tasks(plan_id=plan_id, limit=1)
    if tasks.get("tasks"):
        return tasks["tasks"][0]
    return None


# ---------------------------------------------------------------------------
# AI Analysis & Iteration (P1-8)
# ---------------------------------------------------------------------------

@router.post("/{plan_id}/ai-analyze")
def ai_analyze_results(plan_id: int, db: Session = Depends(get_db)):
    """Analyze simulation results using AI and return insights.

    Returns key metrics summary, parameter sensitivity, anomaly detection,
    and recommendations for next iteration.
    """
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")

    results = (
        db.query(SimulationResult)
        .filter(SimulationResult.plan_id == plan_id)
        .order_by(SimulationResult.run_index.asc())
        .all()
    )
    if not results:
        raise HTTPException(status_code=400, detail="No simulation results to analyze")

    # Compute basic statistics
    ok_results = [r for r in results if r.status == "OK"]
    metrics_list = [r.get_metrics() for r in ok_results]
    params_list = [r.get_params() for r in ok_results]

    if not metrics_list:
        return {"summary": "All points failed", "ok_count": 0, "total": len(results)}

    # Compute metric stats
    def _stats(key: str) -> dict:
        vals = [m.get(key) for m in metrics_list if m.get(key) is not None]
        if not vals:
            return {}
        return {
            "min": min(vals), "max": max(vals),
            "avg": sum(vals) / len(vals),
            "count": len(vals),
        }

    metric_stats = {
        "tavg_nm": _stats("tavg_nm"),
        "ripple_pct": _stats("ripple_pct"),
        "efficiency_pct": _stats("efficiency_pct"),
        "total_losses_w": _stats("total_losses_w"),
    }

    # Find best point by efficiency
    best_idx = -1
    best_eff = -1
    for i, m in enumerate(metrics_list):
        eff = m.get("efficiency_pct", 0)
        if eff and eff > best_eff:
            best_eff = eff
            best_idx = i

    best_point = None
    if best_idx >= 0:
        best_point = {
            "run_index": ok_results[best_idx].run_index,
            "params": params_list[best_idx],
            "metrics": metrics_list[best_idx],
        }

    # Simple parameter sensitivity (correlation-like)
    sensitivity = {}
    param_keys = set()
    for p in params_list:
        param_keys.update(p.keys())
    for pk in param_keys:
        vals = [p.get(pk) for p in params_list if p.get(pk) is not None]
        if len(vals) < 2:
            continue
        effs = [metrics_list[i].get("efficiency_pct", 0) for i, p in enumerate(params_list) if p.get(pk) is not None]
        if len(effs) < 2:
            continue
        # Simple: range of efficiency vs range of param
        p_range = max(vals) - min(vals)
        e_range = max(effs) - min(effs)
        if p_range > 0:
            sensitivity[pk] = round(e_range / p_range, 4)

    # Boundary condition check
    plan_data = plan.get_plan_dict()
    bc = plan_data.get("acceptance_criteria", {})
    constraints = bc.get("hard_constraints", [])
    satisfied = []
    violated = []
    for c in constraints:
        # Simple parse: "metric >= value" or "metric <= value"
        parts = c.replace(">=", ">=").replace("<=", "<=").split()
        if len(parts) >= 3:
            metric, op, val = parts[0], parts[1], float(parts[2])
            stat = metric_stats.get(metric, {})
            if stat:
                if op == ">=" and stat.get("max", 0) >= val:
                    satisfied.append(c)
                elif op == "<=" and stat.get("min", 999) <= val:
                    satisfied.append(c)
                else:
                    violated.append(c)

    return {
        "total_points": len(results),
        "ok_count": len(ok_results),
        "failed_count": len(results) - len(ok_results),
        "metric_stats": metric_stats,
        "best_point": best_point,
        "sensitivity": sensitivity,
        "constraints_satisfied": satisfied,
        "constraints_violated": violated,
        "recommendations": _generate_recommendations(metric_stats, sensitivity, best_point, violated),
    }


def _generate_recommendations(metric_stats: dict, sensitivity: dict, best_point: dict, violated: list) -> list[str]:
    """Generate simple recommendations based on analysis results."""
    recs = []
    eff = metric_stats.get("efficiency_pct", {})
    ripple = metric_stats.get("ripple_pct", {})

    if eff and eff.get("max", 0) < 90:
        recs.append("\u6700\u9ad8\u6548\u7387\u4f4e\u4e8e90%\uff0c\u5efa\u8bae\u51cf\u5c0f\u6c14\u9699\u6216\u589e\u52a0\u78c1\u94a2\u539a\u5ea6\u4ee5\u63d0\u5347\u8f6c\u77e9\u5bc6\u5ea6")
    if ripple and ripple.get("min", 100) > 5:
        recs.append("\u8f6c\u77e9\u8109\u52a8\u504f\u9ad8(>5%)\uff0c\u5efa\u8bae\u626b\u63cf\u78c1\u94a2\u6781\u5f27\u89d2(Magnet_Arc)\u4f18\u5316\u8109\u52a8")
    if sensitivity:
        top_sens = sorted(sensitivity.items(), key=lambda x: abs(x[1]), reverse=True)[:3]
        for pk, sv in top_sens:
            direction = "\u589e\u5927" if sv > 0 else "\u51cf\u5c0f"
            recs.append(f"{pk}\u5bf9\u6548\u7387\u5f71\u54cd\u663e\u8457(\u7075\u654f\u5ea6={sv})\uff0c\u5efa\u8bae\u4e0b\u4e00\u8f6e{direction}\u8be5\u53c2\u6570\u8303\u56f4")
    if best_point:
        recs.append(f"\u5f53\u524d\u6700\u4f18\u70b9: \u6548\u7387{best_point['metrics'].get('efficiency_pct', '?')}%, \u5efa\u8bae\u4ee5\u8be5\u70b9\u53c2\u6570\u4e3a\u4e2d\u5fc3\u7f29\u5c0f\u641c\u7d22\u8303\u56f4")
    if violated:
        recs.append(f"\u6709{len(violated)}\u9879\u7ea6\u675f\u672a\u6ee1\u8db3\uff0c\u5efa\u8bae\u8c03\u6574\u626b\u63cf\u8303\u56f4\u6216\u56fa\u5b9a\u53c2\u6570")
    if not recs:
        recs.append("\u7ed3\u679c\u826f\u597d\uff0c\u5efa\u8bae\u4ee5\u5f53\u524d\u6700\u4f18\u70b9\u4e3a\u4e2d\u5fc3\u8fdb\u884c\u7cbe\u7ec6\u5316\u626b\u63cf")
    return recs


@router.post("/{plan_id}/generate-iteration")
def generate_iteration_plan(plan_id: int, db: Session = Depends(get_db)):
    """Generate next iteration plan based on current results.

    Uses AI analysis to adjust scan ranges and creates a new plan
    with parent_plan_id linking to the current plan.
    """
    plan = db.query(SimulationPlan).filter(SimulationPlan.id == plan_id).first()
    if not plan:
        raise HTTPException(status_code=404, detail="Plan not found")

    results = (
        db.query(SimulationResult)
        .filter(SimulationResult.plan_id == plan_id)
        .order_by(SimulationResult.run_index.asc())
        .all()
    )
    if not results:
        raise HTTPException(status_code=400, detail="No simulation results for iteration")

    plan_data = plan.get_plan_dict()
    ok_results = [r for r in results if r.status == "OK"]
    if not ok_results:
        raise HTTPException(status_code=400, detail="No successful results for iteration")

    # Find best point
    best = max(ok_results, key=lambda r: r.get_metrics().get("efficiency_pct", 0))
    best_params = best.get_params()
    best_metrics = best.get_metrics()

    # Generate new variables: narrow ranges around best point
    new_variables = []
    for v in plan_data.get("variables", []):
        name = v.get("name", "")
        if name in best_params:
            best_val = best_params[name]
            step = v.get("step", 0.1)
            # Narrow to +/- 2 steps around best
            new_start = round(best_val - 2 * step, 6)
            new_stop = round(best_val + 2 * step, 6)
            # Ensure within physical bounds
            new_start = max(new_start, v.get("start", new_start))
            new_stop = min(new_stop, v.get("stop", new_stop))
            values = []
            if new_stop > new_start and step > 0:
                count = int((new_stop - new_start) / step) + 1
                values = [round(new_start + i * step, 6) for i in range(count)]
            new_variables.append({
                **v,
                "start": new_start,
                "stop": new_stop,
                "values": values,
            })
        else:
            new_variables.append(v)

    # Create new plan
    import uuid as _uuid
    new_plan_id = f"SP-{datetime.now().strftime('%Y%m%d-%H%M%S')}-{_uuid.uuid4().hex[:6]}"
    iteration = (plan_data.get("iteration", 1) or 1) + 1
    new_plan_data = {
        **plan_data,
        "plan_id": new_plan_id,
        "iteration": iteration,
        "parent_plan_id": plan.plan_id,
        "variables": new_variables,
        "ai_reasoning": f"Iteration #{iteration}: Narrowed search around best point "
                        f"(eff={best_metrics.get('efficiency_pct', '?')}%, "
                        f"torque={best_metrics.get('tavg_nm', '?')}Nm). "
                        f"Previous best params: {best_params}",
    }

    estimated_points = 1
    for v in new_variables:
        estimated_points *= len(v.get("values", [])) if v.get("values") else 1

    variables_summary = {}
    for v in new_variables:
        variables_summary[v["name"]] = {
            "unit": v.get("unit", ""),
            "values": v.get("values", []),
            "count": len(v.get("values", [])),
        }

    new_plan = SimulationPlan(
        project_id=plan.project_id,
        name=f"{plan.name}_iter{iteration}",
        plan_id=new_plan_id,
        status="draft",
        estimated_points=estimated_points,
        estimated_time_min=estimated_points * 3,
        notes=f"Iteration #{iteration} from plan {plan.plan_id}. Best eff={best_metrics.get('efficiency_pct', '?')}%",
    )
    new_plan.set_plan_dict(new_plan_data)
    new_plan.variables_summary = json.dumps(variables_summary, ensure_ascii=False)
    db.add(new_plan)
    db.commit()
    db.refresh(new_plan)

    return {
        "id": new_plan.id,
        "plan_id": new_plan.plan_id,
        "name": new_plan.name,
        "iteration": iteration,
        "parent_plan_id": plan.plan_id,
        "estimated_points": estimated_points,
        "best_point": {
            "run_index": best.run_index,
            "params": best_params,
            "metrics": best_metrics,
        },
        "message": f"\u8fed\u4ee3\u65b9\u6848\u5df2\u751f\u6210\uff0c\u56f4\u7ed5\u6700\u4f18\u70b9\u7f29\u5c0f\u641c\u7d22\u8303\u56f4\uff0c\u5171{estimated_points}\u4e2a\u6570\u636e\u70b9",
    }