"""
OCR Pipeline Regression Endpoints — FastAPI routes for ground truth and regression.

Extracted from ocr_pipeline_regression.py for modularity.

Lizenz: Apache 2.0
DATENSCHUTZ: Alle Verarbeitung erfolgt lokal.
"""

import json
import logging
import time
from typing import Any, Dict, Optional

from fastapi import APIRouter, HTTPException, Query

from grid_editor_api import _build_grid_core
from ocr_pipeline_session_store import (
    get_session_db,
    list_ground_truth_sessions_db,
    update_session_db,
)
from ocr_pipeline_regression_helpers import (
    _build_reference_snapshot,
    _init_regression_table,
    _persist_regression_run,
    compare_grids,
    get_pool,
)

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/v1/ocr-pipeline", tags=["regression"])


# ---------------------------------------------------------------------------
# Endpoints
# ---------------------------------------------------------------------------

@router.post("/sessions/{session_id}/mark-ground-truth")
async def mark_ground_truth(
    session_id: str,
    pipeline: Optional[str] = Query(None, description="Pipeline used: kombi, pipeline, paddle-direct"),
):
    """Save the current build-grid result as ground-truth reference."""
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    grid_result = session.get("grid_editor_result")
    if not grid_result or not grid_result.get("zones"):
        raise HTTPException(
            status_code=400,
            detail="No grid_editor_result found. Run build-grid first.",
        )

    # Auto-detect pipeline from word_result if not provided
    if not pipeline:
        wr = session.get("word_result") or {}
        engine = wr.get("ocr_engine", "")
        if engine in ("kombi", "rapid_kombi"):
            pipeline = "kombi"
        elif engine == "paddle_direct":
            pipeline = "paddle-direct"
        else:
            pipeline = "pipeline"

    reference = _build_reference_snapshot(grid_result, pipeline=pipeline)

    # Merge into existing ground_truth JSONB
    gt = session.get("ground_truth") or {}
    gt["build_grid_reference"] = reference
    await update_session_db(session_id, ground_truth=gt, current_step=11)

    # Compare with auto-snapshot if available (shows what the user corrected)
    auto_snapshot = gt.get("auto_grid_snapshot")
    correction_diff = None
    if auto_snapshot:
        correction_diff = compare_grids(auto_snapshot, reference)

    logger.info(
        "Ground truth marked for session %s: %d cells (corrections: %s)",
        session_id,
        len(reference["cells"]),
        correction_diff["summary"] if correction_diff else "no auto-snapshot",
    )

    return {
        "status": "ok",
        "session_id": session_id,
        "cells_saved": len(reference["cells"]),
        "summary": reference["summary"],
        "correction_diff": correction_diff,
    }


@router.delete("/sessions/{session_id}/mark-ground-truth")
async def unmark_ground_truth(session_id: str):
    """Remove the ground-truth reference from a session."""
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    gt = session.get("ground_truth") or {}
    if "build_grid_reference" not in gt:
        raise HTTPException(status_code=404, detail="No ground truth reference found")

    del gt["build_grid_reference"]
    await update_session_db(session_id, ground_truth=gt)

    logger.info("Ground truth removed for session %s", session_id)
    return {"status": "ok", "session_id": session_id}


@router.get("/sessions/{session_id}/correction-diff")
async def get_correction_diff(session_id: str):
    """Compare automatic OCR grid with manually corrected ground truth.

    Returns a diff showing exactly which cells the user corrected,
    broken down by col_type (english, german, ipa, etc.).
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    gt = session.get("ground_truth") or {}
    auto_snapshot = gt.get("auto_grid_snapshot")
    reference = gt.get("build_grid_reference")

    if not auto_snapshot:
        raise HTTPException(
            status_code=404,
            detail="No auto_grid_snapshot found. Re-run build-grid to create one.",
        )
    if not reference:
        raise HTTPException(
            status_code=404,
            detail="No ground truth reference found. Mark as ground truth first.",
        )

    diff = compare_grids(auto_snapshot, reference)

    # Enrich with per-col_type breakdown
    col_type_stats: Dict[str, Dict[str, int]] = {}
    for cell_diff in diff.get("cell_diffs", []):
        if cell_diff["type"] != "text_change":
            continue
        # Find col_type from reference cells
        cell_id = cell_diff["cell_id"]
        ref_cell = next(
            (c for c in reference.get("cells", []) if c["cell_id"] == cell_id),
            None,
        )
        ct = ref_cell.get("col_type", "unknown") if ref_cell else "unknown"
        if ct not in col_type_stats:
            col_type_stats[ct] = {"total": 0, "corrected": 0}
        col_type_stats[ct]["corrected"] += 1

    # Count total cells per col_type from reference
    for cell in reference.get("cells", []):
        ct = cell.get("col_type", "unknown")
        if ct not in col_type_stats:
            col_type_stats[ct] = {"total": 0, "corrected": 0}
        col_type_stats[ct]["total"] += 1

    # Calculate accuracy per col_type
    for ct, stats in col_type_stats.items():
        total = stats["total"]
        corrected = stats["corrected"]
        stats["accuracy_pct"] = round((total - corrected) / total * 100, 1) if total > 0 else 100.0

    diff["col_type_breakdown"] = col_type_stats

    return diff


@router.get("/ground-truth-sessions")
async def list_ground_truth_sessions():
    """List all sessions that have a ground-truth reference."""
    sessions = await list_ground_truth_sessions_db()

    result = []
    for s in sessions:
        gt = s.get("ground_truth") or {}
        ref = gt.get("build_grid_reference", {})
        result.append({
            "session_id": s["id"],
            "name": s.get("name", ""),
            "filename": s.get("filename", ""),
            "document_category": s.get("document_category"),
            "pipeline": ref.get("pipeline"),
            "saved_at": ref.get("saved_at"),
            "summary": ref.get("summary", {}),
        })

    return {"sessions": result, "count": len(result)}


@router.post("/sessions/{session_id}/regression/run")
async def run_single_regression(session_id: str):
    """Re-run build_grid for a single session and compare to ground truth."""
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    gt = session.get("ground_truth") or {}
    reference = gt.get("build_grid_reference")
    if not reference:
        raise HTTPException(
            status_code=400,
            detail="No ground truth reference found for this session",
        )

    # Re-compute grid without persisting
    try:
        new_result = await _build_grid_core(session_id, session)
    except (ValueError, Exception) as e:
        return {
            "session_id": session_id,
            "name": session.get("name", ""),
            "status": "error",
            "error": str(e),
        }

    new_snapshot = _build_reference_snapshot(new_result)
    diff = compare_grids(reference, new_snapshot)

    logger.info(
        "Regression test session %s: %s (%d structural, %d cell diffs)",
        session_id, diff["status"],
        diff["summary"]["structural_changes"],
        sum(v for k, v in diff["summary"].items() if k != "structural_changes"),
    )

    return {
        "session_id": session_id,
        "name": session.get("name", ""),
        "status": diff["status"],
        "diff": diff,
        "reference_summary": reference.get("summary", {}),
        "current_summary": new_snapshot.get("summary", {}),
    }


@router.post("/regression/run")
async def run_all_regressions(
    triggered_by: str = Query("manual", description="Who triggered: manual, script, ci"),
):
    """Re-run build_grid for ALL ground-truth sessions and compare."""
    start_time = time.monotonic()
    sessions = await list_ground_truth_sessions_db()

    if not sessions:
        return {
            "status": "pass",
            "message": "No ground truth sessions found",
            "results": [],
            "summary": {"total": 0, "passed": 0, "failed": 0, "errors": 0},
        }

    results = []
    passed = 0
    failed = 0
    errors = 0

    for s in sessions:
        session_id = s["id"]
        gt = s.get("ground_truth") or {}
        reference = gt.get("build_grid_reference")
        if not reference:
            continue

        # Re-load full session (list query may not include all JSONB fields)
        full_session = await get_session_db(session_id)
        if not full_session:
            results.append({
                "session_id": session_id,
                "name": s.get("name", ""),
                "status": "error",
                "error": "Session not found during re-load",
            })
            errors += 1
            continue

        try:
            new_result = await _build_grid_core(session_id, full_session)
        except (ValueError, Exception) as e:
            results.append({
                "session_id": session_id,
                "name": s.get("name", ""),
                "status": "error",
                "error": str(e),
            })
            errors += 1
            continue

        new_snapshot = _build_reference_snapshot(new_result)
        diff = compare_grids(reference, new_snapshot)

        entry = {
            "session_id": session_id,
            "name": s.get("name", ""),
            "status": diff["status"],
            "diff_summary": diff["summary"],
            "reference_summary": reference.get("summary", {}),
            "current_summary": new_snapshot.get("summary", {}),
        }

        # Include full diffs only for failures (keep response compact)
        if diff["status"] == "fail":
            entry["structural_diffs"] = diff["structural_diffs"]
            entry["cell_diffs"] = diff["cell_diffs"]
            failed += 1
        else:
            passed += 1

        results.append(entry)

    overall = "pass" if failed == 0 and errors == 0 else "fail"
    duration_ms = int((time.monotonic() - start_time) * 1000)

    summary = {
        "total": len(results),
        "passed": passed,
        "failed": failed,
        "errors": errors,
    }

    logger.info(
        "Regression suite: %s — %d passed, %d failed, %d errors (of %d) in %dms",
        overall, passed, failed, errors, len(results), duration_ms,
    )

    # Persist to DB
    run_id = await _persist_regression_run(
        status=overall,
        summary=summary,
        results=results,
        duration_ms=duration_ms,
        triggered_by=triggered_by,
    )

    return {
        "status": overall,
        "run_id": run_id,
        "duration_ms": duration_ms,
        "results": results,
        "summary": summary,
    }


@router.get("/regression/history")
async def get_regression_history(
    limit: int = Query(20, ge=1, le=100),
):
    """Get recent regression run history from the database."""
    try:
        await _init_regression_table()
        pool = await get_pool()
        async with pool.acquire() as conn:
            rows = await conn.fetch(
                """
                SELECT id, run_at, status, total, passed, failed, errors,
                       duration_ms, triggered_by
                FROM regression_runs
                ORDER BY run_at DESC
                LIMIT $1
                """,
                limit,
            )
        return {
            "runs": [
                {
                    "id": str(row["id"]),
                    "run_at": row["run_at"].isoformat() if row["run_at"] else None,
                    "status": row["status"],
                    "total": row["total"],
                    "passed": row["passed"],
                    "failed": row["failed"],
                    "errors": row["errors"],
                    "duration_ms": row["duration_ms"],
                    "triggered_by": row["triggered_by"],
                }
                for row in rows
            ],
            "count": len(rows),
        }
    except Exception as e:
        logger.warning("Failed to fetch regression history: %s", e)
        return {"runs": [], "count": 0, "error": str(e)}


@router.get("/regression/history/{run_id}")
async def get_regression_run_detail(run_id: str):
    """Get detailed results of a specific regression run."""
    try:
        await _init_regression_table()
        pool = await get_pool()
        async with pool.acquire() as conn:
            row = await conn.fetchrow(
                "SELECT * FROM regression_runs WHERE id = $1",
                run_id,
            )
        if not row:
            raise HTTPException(status_code=404, detail="Run not found")
        return {
            "id": str(row["id"]),
            "run_at": row["run_at"].isoformat() if row["run_at"] else None,
            "status": row["status"],
            "total": row["total"],
            "passed": row["passed"],
            "failed": row["failed"],
            "errors": row["errors"],
            "duration_ms": row["duration_ms"],
            "triggered_by": row["triggered_by"],
            "results": json.loads(row["results"]) if row["results"] else [],
        }
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))