"""
Pending deployments — field-captured "I just installed this seismograph"
records waiting to be classified into a project + location.

Routes:
  POST /api/deployments/capture                 — capture a new pending deployment
  GET  /api/deployments/pending                 — list awaiting captures
  GET  /api/deployments/pending/{id}            — single capture detail
  POST /api/deployments/pending/{id}/promote    — classify → create UnitAssignment
  POST /api/deployments/pending/{id}/cancel     — abandon

See backend/models.py PendingDeployment docstring for the full lifecycle.

Seismograph-only for v1; capture refuses if unit_id is anything else.
"""

from __future__ import annotations

import shutil
import uuid
from datetime import datetime
from pathlib import Path
from typing import Optional

from fastapi import APIRouter, Depends, File, Form, HTTPException, Request, UploadFile
from fastapi.responses import JSONResponse
from sqlalchemy.orm import Session

from backend.database import get_db
from backend.models import (
    PendingDeployment,
    RosterUnit,
    Project,
    MonitoringLocation,
    UnitAssignment,
    UnitHistory,
)
from backend.routers.photos import extract_exif_data

router = APIRouter(prefix="/api/deployments", tags=["pending-deployments"])

PHOTOS_BASE_DIR = Path("data/photos")
_ALLOWED_PHOTO_EXTS = {".jpg", ".jpeg", ".png", ".gif", ".webp", ".heic", ".heif"}


def _record_history(
    db: Session,
    unit_id: str,
    change_type: str,
    *,
    old_value: Optional[str] = None,
    new_value: Optional[str] = None,
    notes: Optional[str] = None,
    source: str = "manual",
) -> None:
    """Mirror of project_locations._record_assignment_history — kept local
    so this router doesn't depend on a project_locations import cycle."""
    db.add(UnitHistory(
        unit_id=unit_id,
        change_type=change_type,
        field_name="pending_deployment",
        old_value=old_value,
        new_value=new_value,
        changed_at=datetime.utcnow(),
        source=source,
        notes=notes,
    ))


@router.post("/capture")
async def capture_deployment(
    unit_id: str           = Form(...),
    operator_note: str     = Form(""),
    captured_at_iso: str   = Form(""),
    photo: UploadFile      = File(...),
    db: Session            = Depends(get_db),
):
    """Field-capture endpoint.

    Multipart form:
      unit_id          — seismograph being deployed
      operator_note    — optional free-text site memo
      captured_at_iso  — optional override of the capture timestamp
                          (default: photo's EXIF DateTimeOriginal, or now)
      photo            — install photo (EXIF GPS extracted if present)

    Refuses if unit_id isn't a seismograph (SLM deployments don't follow
    the same field-install pattern).
    """
    unit = db.query(RosterUnit).filter_by(id=unit_id).first()
    if not unit:
        raise HTTPException(status_code=404, detail=f"Unit {unit_id!r} not found.")
    if unit.device_type != "seismograph":
        raise HTTPException(
            status_code=400,
            detail=f"Pending deployments are for seismographs only "
                   f"(this unit is {unit.device_type}).",
        )

    # Validate + save the photo.
    file_ext = Path(photo.filename or "photo.jpg").suffix.lower()
    if file_ext not in _ALLOWED_PHOTO_EXTS:
        raise HTTPException(
            status_code=400,
            detail=f"Invalid photo type {file_ext!r}. Allowed: {sorted(_ALLOWED_PHOTO_EXTS)}",
        )

    unit_photo_dir = PHOTOS_BASE_DIR / unit_id
    unit_photo_dir.mkdir(parents=True, exist_ok=True)

    capture_id = str(uuid.uuid4())
    ts_str   = datetime.now().strftime("%Y%m%d_%H%M%S")
    filename = f"install_{ts_str}_{capture_id[:8]}{file_ext}"
    file_path = unit_photo_dir / filename

    try:
        with open(file_path, "wb") as buf:
            shutil.copyfileobj(photo.file, buf)
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to save photo: {e}")

    # Extract EXIF — best-effort.  No EXIF / no GPS is fine; operator
    # can fill coordinates manually later in the promote step.
    metadata = extract_exif_data(file_path)
    coords        = metadata.get("coordinates")          # "lat,lon" or None
    photo_ts      = metadata.get("timestamp")            # datetime or None

    if captured_at_iso:
        try:
            captured_at = datetime.fromisoformat(captured_at_iso)
        except ValueError:
            raise HTTPException(status_code=400, detail=f"Invalid captured_at_iso: {captured_at_iso!r}")
    elif photo_ts:
        captured_at = photo_ts
    else:
        captured_at = datetime.utcnow()

    pd = PendingDeployment(
        id              = capture_id,
        unit_id         = unit_id,
        captured_at     = captured_at,
        coordinates     = coords,
        operator_note   = (operator_note or "").strip() or None,
        photo_filename  = filename,
        status          = "awaiting",
    )
    db.add(pd)

    _record_history(
        db, unit_id=unit_id,
        change_type="pending_deployment_captured",
        new_value=f"awaiting classification @ {captured_at:%Y-%m-%d %H:%M}"
                  + (f" • {coords}" if coords else ""),
        notes=(operator_note or None),
    )

    db.commit()
    db.refresh(pd)

    return JSONResponse({
        "success":           True,
        "pending_deployment": _to_dict(pd, unit=unit),
        "photo_url":          f"/api/unit/{unit_id}/photo/{filename}",
        "extracted_coords":   coords,
        "extracted_timestamp": photo_ts.isoformat() if photo_ts else None,
    })


@router.get("/pending")
def list_pending(
    status: str = "awaiting",
    db: Session = Depends(get_db),
):
    """List pending deployments by status (default: awaiting classification)."""
    rows = (
        db.query(PendingDeployment)
        .filter_by(status=status)
        .order_by(PendingDeployment.captured_at.desc())
        .all()
    )
    # Bulk-resolve unit references in one query (avoid N+1).
    unit_ids = {r.unit_id for r in rows}
    units = {u.id: u for u in db.query(RosterUnit).filter(RosterUnit.id.in_(unit_ids)).all()} \
            if unit_ids else {}
    return {
        "count":               len(rows),
        "status":              status,
        "pending_deployments": [_to_dict(r, unit=units.get(r.unit_id)) for r in rows],
    }


@router.get("/pending/{pending_id}")
def get_pending(pending_id: str, db: Session = Depends(get_db)):
    pd = db.query(PendingDeployment).filter_by(id=pending_id).first()
    if not pd:
        raise HTTPException(status_code=404, detail="Pending deployment not found.")
    unit = db.query(RosterUnit).filter_by(id=pd.unit_id).first()
    return _to_dict(pd, unit=unit, detail=True)


@router.post("/pending/{pending_id}/promote")
async def promote_pending(
    pending_id: str,
    request: Request,
    db: Session = Depends(get_db),
):
    """Classify a pending deployment → create a UnitAssignment.

    Body JSON — one of two shapes:

      1. Assign to existing location:
         {
           "location_id": "<uuid>",
           "notes": "<optional>"
         }

      2. Create a new location under (existing or new) project:
         {
           "project_id":      "<existing>" | null,   # null means create new
           "project_name":    "<required if project_id is null>",
           "project_type_id": "<existing project_type id, e.g. 'vibration_monitoring'>",
                                                    # required if creating new project
           "location_name":   "<required>",
           "use_captured_coords": true | false,     # default true — write the
                                                    # pending's coordinates onto
                                                    # the new location
           "notes": "<optional>"
         }

    Status flips to "assigned"; resulting_assignment_id is populated.
    """
    pd = db.query(PendingDeployment).filter_by(id=pending_id).first()
    if not pd:
        raise HTTPException(status_code=404, detail="Pending deployment not found.")
    if pd.status != "awaiting":
        raise HTTPException(
            status_code=400,
            detail=f"Pending deployment is {pd.status!r}, not awaiting — already classified?",
        )

    try:
        payload = await request.json()
    except Exception:
        raise HTTPException(status_code=400, detail="Invalid JSON body.")

    notes = (payload.get("notes") or "").strip() or None

    # Resolve / create the location.
    location_id = payload.get("location_id")
    if location_id:
        location = db.query(MonitoringLocation).filter_by(id=location_id).first()
        if not location:
            raise HTTPException(status_code=404, detail=f"Location {location_id!r} not found.")
        project_id = location.project_id
    else:
        # Create-new path.  Need a project (existing or new).
        project_id = payload.get("project_id")
        if not project_id:
            project_name = (payload.get("project_name") or "").strip()
            project_type_id = (payload.get("project_type_id") or "").strip()
            if not project_name:
                raise HTTPException(
                    status_code=400,
                    detail="Either project_id, or project_name + project_type_id, required.",
                )
            if not project_type_id:
                raise HTTPException(
                    status_code=400,
                    detail="project_type_id required when creating a new project.",
                )
            new_project = Project(
                id=str(uuid.uuid4()),
                name=project_name,
                project_type_id=project_type_id,
                status="active",
            )
            db.add(new_project)
            db.flush()
            project_id = new_project.id

        loc_name = (payload.get("location_name") or "").strip()
        if not loc_name:
            raise HTTPException(status_code=400, detail="location_name required.")
        use_coords = payload.get("use_captured_coords", True)
        location = MonitoringLocation(
            id=str(uuid.uuid4()),
            project_id=project_id,
            location_type="vibration",          # seismographs only
            name=loc_name,
            coordinates=(pd.coordinates if use_coords else None),
        )
        db.add(location)
        db.flush()

    # Create the assignment.  assigned_at = pending capture time (so
    # events emitted after the install are correctly attributed back
    # to this location).
    assignment = UnitAssignment(
        id=str(uuid.uuid4()),
        unit_id=pd.unit_id,
        location_id=location.id,
        project_id=project_id,
        device_type="seismograph",
        assigned_at=pd.captured_at,
        assigned_until=None,
        status="active",
        notes=notes,
        source="manual",
    )
    db.add(assignment)
    db.flush()

    # Promote the pending row.
    pd.status                   = "assigned"
    pd.promoted_at              = datetime.utcnow()
    pd.resulting_assignment_id  = assignment.id
    pd.updated_at               = datetime.utcnow()

    _record_history(
        db, unit_id=pd.unit_id,
        change_type="pending_deployment_promoted",
        old_value="awaiting",
        new_value=f"{location.name} (assignment {assignment.id[:8]})",
        notes=notes,
    )

    db.commit()
    db.refresh(pd)
    db.refresh(assignment)

    return {
        "success":          True,
        "assignment_id":    assignment.id,
        "location_id":      location.id,
        "project_id":       project_id,
        "promoted_at":      pd.promoted_at.isoformat(),
    }


@router.post("/pending/{pending_id}/cancel")
async def cancel_pending(
    pending_id: str,
    request: Request,
    db: Session = Depends(get_db),
):
    """Mark a pending deployment as cancelled (operator captured by mistake)."""
    pd = db.query(PendingDeployment).filter_by(id=pending_id).first()
    if not pd:
        raise HTTPException(status_code=404, detail="Pending deployment not found.")
    if pd.status != "awaiting":
        raise HTTPException(
            status_code=400,
            detail=f"Pending deployment is {pd.status!r}, not awaiting.",
        )

    try:
        payload = await request.json()
    except Exception:
        payload = {}
    reason = (payload.get("reason") or "").strip() or None

    pd.status            = "cancelled"
    pd.cancelled_at      = datetime.utcnow()
    pd.cancelled_reason  = reason
    pd.updated_at        = datetime.utcnow()

    _record_history(
        db, unit_id=pd.unit_id,
        change_type="pending_deployment_cancelled",
        old_value="awaiting",
        new_value="cancelled",
        notes=reason,
    )

    db.commit()
    return {"success": True, "cancelled_at": pd.cancelled_at.isoformat()}


# ── Helpers ───────────────────────────────────────────────────────────────────

def _to_dict(pd: PendingDeployment, unit: Optional[RosterUnit] = None, detail: bool = False) -> dict:
    out = {
        "id":             pd.id,
        "unit_id":        pd.unit_id,
        "captured_at":    pd.captured_at.isoformat() if pd.captured_at else None,
        "coordinates":    pd.coordinates,
        "operator_note":  pd.operator_note,
        "photo_filename": pd.photo_filename,
        "photo_url":      f"/api/unit/{pd.unit_id}/photo/{pd.photo_filename}"
                          if pd.photo_filename else None,
        "status":         pd.status,
        "created_at":     pd.created_at.isoformat() if pd.created_at else None,
    }
    if pd.status == "assigned":
        out["promoted_at"]             = pd.promoted_at.isoformat() if pd.promoted_at else None
        out["resulting_assignment_id"] = pd.resulting_assignment_id
    if pd.status == "cancelled":
        out["cancelled_at"]     = pd.cancelled_at.isoformat() if pd.cancelled_at else None
        out["cancelled_reason"] = pd.cancelled_reason

    if unit:
        out["unit"] = {
            "id":          unit.id,
            "device_type": unit.device_type,
            "note":        unit.note,
            "deployed":    unit.deployed,
        }
    return out