"""
Grid Editor API — endpoints for grid building, editing, and export.

The core grid building logic is in grid_build_core.py.
"""

import logging
import re
import time
from typing import Any, Dict, List, Optional, Tuple

from fastapi import APIRouter, HTTPException, Query, Request

from grid_build_core import _build_grid_core
from grid_editor_helpers import _words_in_zone
from ocr_pipeline_session_store import (
    get_session_db,
    update_session_db,
)

logger = logging.getLogger(__name__)

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


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

@router.post("/sessions/{session_id}/build-grid")
async def build_grid(
    session_id: str,
    ipa_mode: str = Query("auto", pattern="^(auto|all|de|en|none)$"),
    syllable_mode: str = Query("auto", pattern="^(auto|all|de|en|none)$"),
):
    """Build a structured, zone-aware grid from existing Kombi word results.

    Requires that paddle-kombi or rapid-kombi has already been run on the session.
    Uses the image for box detection and the word positions for grid structuring.

    Query params:
        ipa_mode: "auto" (only when English IPA detected), "all" (force), "none" (skip)
        syllable_mode: "auto" (only when original has dividers), "all" (force), "none" (skip)

    Returns a StructuredGrid with zones, each containing their own
    columns, rows, and cells — ready for the frontend Excel-like editor.
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    try:
        result = await _build_grid_core(
            session_id, session,
            ipa_mode=ipa_mode, syllable_mode=syllable_mode,
        )
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e))

    # Save automatic grid snapshot for later comparison with manual corrections
    # Lazy import to avoid circular dependency with ocr_pipeline_regression
    from ocr_pipeline_regression import _build_reference_snapshot

    wr = session.get("word_result") or {}
    engine = wr.get("ocr_engine", "")
    if engine in ("kombi", "rapid_kombi"):
        auto_pipeline = "kombi"
    elif engine == "paddle_direct":
        auto_pipeline = "paddle-direct"
    else:
        auto_pipeline = "pipeline"
    auto_snapshot = _build_reference_snapshot(result, pipeline=auto_pipeline)

    gt = session.get("ground_truth") or {}
    gt["auto_grid_snapshot"] = auto_snapshot

    # Persist to DB and advance current_step to 11 (reconstruction complete)
    await update_session_db(session_id, grid_editor_result=result, ground_truth=gt, current_step=11)

    logger.info(
        "build-grid session %s: %d zones, %d cols, %d rows, %d cells, "
        "%d boxes in %.2fs",
        session_id,
        len(result.get("zones", [])),
        result.get("summary", {}).get("total_columns", 0),
        result.get("summary", {}).get("total_rows", 0),
        result.get("summary", {}).get("total_cells", 0),
        result.get("boxes_detected", 0),
        result.get("duration_seconds", 0),
    )

    return result


@router.post("/sessions/{session_id}/save-grid")
async def save_grid(session_id: str, request: Request):
    """Save edited grid data from the frontend Excel-like editor.

    Receives the full StructuredGrid with user edits (text changes,
    formatting changes like bold columns, header rows, etc.) and
    persists it to the session's grid_editor_result.
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    body = await request.json()

    # Validate basic structure
    if "zones" not in body:
        raise HTTPException(status_code=400, detail="Missing 'zones' in request body")

    # Preserve metadata from the original build
    existing = session.get("grid_editor_result") or {}
    result = {
        "session_id": session_id,
        "image_width": body.get("image_width", existing.get("image_width", 0)),
        "image_height": body.get("image_height", existing.get("image_height", 0)),
        "zones": body["zones"],
        "boxes_detected": body.get("boxes_detected", existing.get("boxes_detected", 0)),
        "summary": body.get("summary", existing.get("summary", {})),
        "formatting": body.get("formatting", existing.get("formatting", {})),
        "duration_seconds": existing.get("duration_seconds", 0),
        "edited": True,
    }

    await update_session_db(session_id, grid_editor_result=result, current_step=11)

    logger.info("save-grid session %s: %d zones saved", session_id, len(body["zones"]))

    return {"session_id": session_id, "saved": True}


@router.get("/sessions/{session_id}/grid-editor")
async def get_grid(session_id: str):
    """Retrieve the current grid editor state for a session."""
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    result = session.get("grid_editor_result")
    if not result:
        raise HTTPException(
            status_code=404,
            detail="No grid editor data. Run build-grid first.",
        )

    return result


# ---------------------------------------------------------------------------
# Gutter Repair endpoints
# ---------------------------------------------------------------------------

@router.post("/sessions/{session_id}/gutter-repair")
async def gutter_repair(session_id: str):
    """Analyse grid for gutter-edge OCR errors and return repair suggestions.

    Detects:
      - Words truncated/blurred at the book binding (spell_fix)
      - Words split across rows with missing hyphen chars (hyphen_join)
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    grid_data = session.get("grid_editor_result")
    if not grid_data:
        raise HTTPException(
            status_code=400,
            detail="No grid data. Run build-grid first.",
        )

    from cv_gutter_repair import analyse_grid_for_gutter_repair

    image_width = grid_data.get("image_width", 0)
    result = analyse_grid_for_gutter_repair(grid_data, image_width=image_width)

    # Persist suggestions in ground_truth.gutter_repair (avoids DB migration)
    gt = session.get("ground_truth") or {}
    gt["gutter_repair"] = result
    await update_session_db(session_id, ground_truth=gt)

    logger.info(
        "gutter-repair session %s: %d suggestions in %.2fs",
        session_id,
        result.get("stats", {}).get("suggestions_found", 0),
        result.get("duration_seconds", 0),
    )

    return result


@router.post("/sessions/{session_id}/gutter-repair/apply")
async def gutter_repair_apply(session_id: str, request: Request):
    """Apply accepted gutter repair suggestions to the grid.

    Body: { "accepted": ["suggestion_id_1", "suggestion_id_2", ...] }
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    grid_data = session.get("grid_editor_result")
    if not grid_data:
        raise HTTPException(status_code=400, detail="No grid data.")

    gt = session.get("ground_truth") or {}
    gutter_result = gt.get("gutter_repair")
    if not gutter_result:
        raise HTTPException(
            status_code=400,
            detail="No gutter repair data. Run gutter-repair first.",
        )

    body = await request.json()
    accepted_ids = body.get("accepted", [])
    if not accepted_ids:
        return {"applied_count": 0, "changes": []}

    # text_overrides: { suggestion_id: "alternative_text" }
    # Allows the user to pick a different correction from the alternatives list
    text_overrides = body.get("text_overrides", {})

    from cv_gutter_repair import apply_gutter_suggestions

    suggestions = gutter_result.get("suggestions", [])

    # Apply user-selected alternatives before passing to apply
    for s in suggestions:
        sid = s.get("id", "")
        if sid in text_overrides and text_overrides[sid]:
            s["suggested_text"] = text_overrides[sid]

    result = apply_gutter_suggestions(grid_data, accepted_ids, suggestions)

    # Save updated grid back to session
    await update_session_db(session_id, grid_editor_result=grid_data)

    logger.info(
        "gutter-repair/apply session %s: %d changes applied",
        session_id,
        result.get("applied_count", 0),
    )

    return result


# ---------------------------------------------------------------------------
# Box-Grid-Review endpoints
# ---------------------------------------------------------------------------

@router.post("/sessions/{session_id}/build-box-grids")
async def build_box_grids(session_id: str, request: Request):
    """Rebuild grid structure for all detected boxes with layout-aware detection.

    Uses structure_result.boxes (from Step 7) as the source of box coordinates,
    and raw_paddle_words as OCR word source. Creates or updates box zones in
    the grid_editor_result.

    Optional body: { "overrides": { "0": "bullet_list" } }
    Maps box_index → forced layout_type.
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    grid_data = session.get("grid_editor_result")
    if not grid_data:
        raise HTTPException(status_code=400, detail="No grid data. Run build-grid first.")

    # Get raw OCR words (with top/left/width/height keys)
    word_result = session.get("word_result") or {}
    all_words = word_result.get("raw_paddle_words") or word_result.get("raw_tesseract_words") or []
    if not all_words:
        raise HTTPException(status_code=400, detail="No raw OCR words available.")

    # Get detected boxes from structure_result
    structure_result = session.get("structure_result") or {}
    gt = session.get("ground_truth") or {}
    if not structure_result:
        structure_result = gt.get("structure_result") or {}
    detected_boxes = structure_result.get("boxes") or []
    if not detected_boxes:
        return {"session_id": session_id, "box_zones_rebuilt": 0, "spell_fixes": 0, "message": "No boxes detected"}

    # Filter out false-positive boxes in header/footer margins.
    # Textbook pages have ~2.5cm margins at top/bottom. At typical scan
    # resolutions (150-300 DPI), that's roughly 5-10% of image height.
    # A box whose vertical CENTER falls within the top or bottom 7% of
    # the image is likely a page number, unit header, or running footer.
    img_h_for_filter = grid_data.get("image_height", 0) or word_result.get("image_height", 0)
    if img_h_for_filter > 0:
        margin_frac = 0.07  # 7% of image height
        margin_top = img_h_for_filter * margin_frac
        margin_bottom = img_h_for_filter * (1 - margin_frac)
        filtered = []
        for box in detected_boxes:
            by = box.get("y", 0)
            bh = box.get("h", 0)
            box_center_y = by + bh / 2
            if box_center_y < margin_top or box_center_y > margin_bottom:
                logger.info("build-box-grids: skipping header/footer box at y=%d h=%d (center=%.0f, margins=%.0f/%.0f)",
                            by, bh, box_center_y, margin_top, margin_bottom)
                continue
            filtered.append(box)
        detected_boxes = filtered

    body = {}
    try:
        body = await request.json()
    except Exception:
        pass
    layout_overrides = body.get("overrides", {})

    from cv_box_layout import build_box_zone_grid
    from grid_editor_helpers import _words_in_zone

    img_w = grid_data.get("image_width", 0) or word_result.get("image_width", 0)
    img_h = grid_data.get("image_height", 0) or word_result.get("image_height", 0)

    zones = grid_data.get("zones", [])

    # Find highest existing zone_index
    max_zone_idx = max((z.get("zone_index", 0) for z in zones), default=-1)

    # Remove old box zones (we'll rebuild them)
    zones = [z for z in zones if z.get("zone_type") != "box"]

    box_count = 0
    spell_fixes = 0

    for box_idx, box in enumerate(detected_boxes):
        bx = box.get("x", 0)
        by = box.get("y", 0)
        bw = box.get("w", 0)
        bh = box.get("h", 0)

        if bw <= 0 or bh <= 0:
            continue

        # Filter raw OCR words inside this box
        zone_words = _words_in_zone(all_words, by, bh, bx, bw)
        if not zone_words:
            logger.info("Box %d: no words found in bbox (%d,%d,%d,%d)", box_idx, bx, by, bw, bh)
            continue

        zone_idx = max_zone_idx + 1 + box_idx
        forced_layout = layout_overrides.get(str(box_idx))

        # Build box grid
        box_grid = build_box_zone_grid(
            zone_words, bx, by, bw, bh,
            zone_idx, img_w, img_h,
            layout_type=forced_layout,
        )

        # Apply SmartSpellChecker to all box cells
        try:
            from smart_spell import SmartSpellChecker
            ssc = SmartSpellChecker()
            for cell in box_grid.get("cells", []):
                text = cell.get("text", "")
                if not text:
                    continue
                result = ssc.correct_text(text, lang="auto")
                if result.changed:
                    cell["text"] = result.corrected
                    spell_fixes += 1
        except ImportError:
            pass

        # Build zone entry
        zone_entry = {
            "zone_index": zone_idx,
            "zone_type": "box",
            "bbox_px": {"x": bx, "y": by, "w": bw, "h": bh},
            "bbox_pct": {
                "x": round(bx / img_w * 100, 2) if img_w else 0,
                "y": round(by / img_h * 100, 2) if img_h else 0,
                "w": round(bw / img_w * 100, 2) if img_w else 0,
                "h": round(bh / img_h * 100, 2) if img_h else 0,
            },
            "border": None,
            "word_count": len(zone_words),
            "columns": box_grid["columns"],
            "rows": box_grid["rows"],
            "cells": box_grid["cells"],
            "header_rows": box_grid.get("header_rows", []),
            "box_layout_type": box_grid.get("box_layout_type", "flowing"),
            "box_grid_reviewed": False,
            "box_bg_color": box.get("bg_color_name", ""),
            "box_bg_hex": box.get("bg_color_hex", ""),
        }
        zones.append(zone_entry)
        box_count += 1

    # Sort zones by y-position for correct reading order
    zones.sort(key=lambda z: z.get("bbox_px", {}).get("y", 0))

    grid_data["zones"] = zones
    await update_session_db(session_id, grid_editor_result=grid_data)

    logger.info(
        "build-box-grids session %s: %d boxes processed (%d words spell-fixed) from %d detected",
        session_id, box_count, spell_fixes, len(detected_boxes),
    )

    return {
        "session_id": session_id,
        "box_zones_rebuilt": box_count,
        "total_detected_boxes": len(detected_boxes),
        "spell_fixes": spell_fixes,
        "zones": zones,
    }


# ---------------------------------------------------------------------------
# Unified Grid endpoint
# ---------------------------------------------------------------------------

@router.post("/sessions/{session_id}/build-unified-grid")
async def build_unified_grid_endpoint(session_id: str):
    """Build a single-zone unified grid merging content + box zones.

    Takes the existing multi-zone grid_editor_result and produces a
    unified grid where boxes are integrated into the main row sequence.
    Persists as unified_grid_result (preserves original multi-zone data).
    """
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    grid_data = session.get("grid_editor_result")
    if not grid_data:
        raise HTTPException(status_code=400, detail="No grid data. Run build-grid first.")

    from unified_grid import build_unified_grid

    result = build_unified_grid(
        zones=grid_data.get("zones", []),
        image_width=grid_data.get("image_width", 0),
        image_height=grid_data.get("image_height", 0),
        layout_metrics=grid_data.get("layout_metrics", {}),
    )

    # Persist as separate field (don't overwrite original multi-zone grid)
    await update_session_db(session_id, unified_grid_result=result)

    logger.info(
        "build-unified-grid session %s: %d rows, %d cells",
        session_id,
        result.get("summary", {}).get("total_rows", 0),
        result.get("summary", {}).get("total_cells", 0),
    )

    return result


@router.get("/sessions/{session_id}/unified-grid")
async def get_unified_grid(session_id: str):
    """Retrieve the unified grid for a session."""
    session = await get_session_db(session_id)
    if not session:
        raise HTTPException(status_code=404, detail=f"Session {session_id} not found")

    result = session.get("unified_grid_result")
    if not result:
        raise HTTPException(
            status_code=404,
            detail="No unified grid. Run build-unified-grid first.",
        )

    return result