"""
SQLite-backed curation index.

Why SQLite:
- fast ad-hoc queries over large local datasets
- incremental updates (skip unchanged bundles)
- no extra dependencies
"""

from __future__ import annotations

import json
import os
import sqlite3
import time
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Dict, Literal, Optional

from .indexer import CurationIndexConfig, _bundle_row, _discover_bundles


@dataclass(frozen=True)
class SQLiteIndexConfig:
    workers: int = 8
    incremental: bool = True
    include_depth_stream_summary: bool = True
    discover: Literal["children", "recursive"] = "children"


def _now_s() -> float:
    return float(time.time())


def _connect(db_path: Path) -> sqlite3.Connection:
    p = Path(db_path)
    p.parent.mkdir(parents=True, exist_ok=True)
    conn = sqlite3.connect(str(p))
    conn.execute("PRAGMA journal_mode=WAL;")
    conn.execute("PRAGMA synchronous=NORMAL;")
    conn.execute("PRAGMA temp_store=MEMORY;")
    conn.execute("PRAGMA foreign_keys=ON;")
    return conn


def _ensure_column(conn: sqlite3.Connection, *, table: str, column: str, decl: str) -> None:
    """
    Best-effort migration helper: add a column if it doesn't exist.
    """
    cols = [r[1] for r in conn.execute(f"PRAGMA table_info({table});").fetchall()]
    if str(column) not in cols:
        conn.execute(f"ALTER TABLE {table} ADD COLUMN {column} {decl};")


def _ensure_schema(conn: sqlite3.Connection) -> None:
    conn.execute(
        """
        CREATE TABLE IF NOT EXISTS bundles (
          bundle_dir TEXT PRIMARY KEY,
          capture_id TEXT,
          created_at TEXT,
          scene_type TEXT,
          operating_regime TEXT,
          source_format TEXT,
          has_packed_depth INTEGER,
          num_devices INTEGER,
          default_device_id TEXT,
          teacher_depth_count INTEGER,
          teacher_depth_mtime_ns INTEGER,
          manifest_mtime_ns INTEGER,
          manifest_size INTEGER,
          indexed_at_unix_s REAL,
          row_json TEXT
        );
        """
    )
    conn.execute(
        """
        CREATE TABLE IF NOT EXISTS devices (
          bundle_dir TEXT NOT NULL,
          device_id TEXT NOT NULL,
          video_path TEXT,
          video_size_bytes INTEGER,
          intrinsics_path TEXT,
          timestamps_path TEXT,
          packed_depth_index_path TEXT,
          packed_depth_frames_count INTEGER,
          packed_depth_gaps INTEGER,
          PRIMARY KEY (bundle_dir, device_id),
          FOREIGN KEY (bundle_dir) REFERENCES bundles(bundle_dir) ON DELETE CASCADE
        );
        """
    )
    conn.execute("CREATE INDEX IF NOT EXISTS idx_bundles_scene ON bundles(scene_type);")
    conn.execute(
        "CREATE INDEX IF NOT EXISTS idx_bundles_packed_depth ON bundles(has_packed_depth);"
    )
    conn.execute("CREATE INDEX IF NOT EXISTS idx_bundles_source ON bundles(source_format);")
    conn.execute(
        "CREATE INDEX IF NOT EXISTS idx_bundles_teacher_depth ON bundles(teacher_depth_count);"
    )

    # Migrations for older DBs that predate these columns.
    _ensure_column(conn, table="bundles", column="default_device_id", decl="TEXT")
    _ensure_column(conn, table="bundles", column="teacher_depth_count", decl="INTEGER")
    _ensure_column(conn, table="bundles", column="teacher_depth_mtime_ns", decl="INTEGER")


def _teacher_depth_stats(bundle_dir: Path) -> tuple[int, int]:
    """
    Return (teacher_depth_count, teacher_depth_mtime_ns).
    """
    depth_dir = Path(bundle_dir) / "teacher_outputs" / "depth"
    if not depth_dir.exists() or not depth_dir.is_dir():
        return 0, 0
    try:
        st = depth_dir.stat()
        mtime_ns = int(getattr(st, "st_mtime_ns", int(st.st_mtime * 1e9)))
    except Exception:
        mtime_ns = 0
    try:
        n = 0
        for ent in os.scandir(depth_dir):
            if not ent.is_file():
                continue
            name = ent.name
            if name.startswith("frame_") and name.endswith(".npy"):
                n += 1
        return int(n), int(mtime_ns)
    except Exception:
        return 0, int(mtime_ns)


def _existing_manifest_stats(conn: sqlite3.Connection) -> Dict[str, Dict[str, int]]:
    cur = conn.execute(
        "SELECT bundle_dir, manifest_mtime_ns, manifest_size, "
        "COALESCE(teacher_depth_count,0), COALESCE(teacher_depth_mtime_ns,0) "
        "FROM bundles;"
    )
    out: Dict[str, Dict[str, int]] = {}
    for bdir, mtime_ns, size, td_count, td_mtime_ns in cur.fetchall():
        if bdir:
            out[str(bdir)] = {
                "manifest_mtime_ns": int(mtime_ns or 0),
                "manifest_size": int(size or 0),
                "teacher_depth_count": int(td_count or 0),
                "teacher_depth_mtime_ns": int(td_mtime_ns or 0),
            }
    return out


def _upsert_row(
    conn: sqlite3.Connection,
    *,
    row: Dict[str, Any],
    manifest_mtime_ns: int,
    manifest_size: int,
    teacher_depth_count: int,
    teacher_depth_mtime_ns: int,
) -> None:
    bdir = str(row.get("bundle_dir", ""))
    capture_id = row.get("capture_id")
    created_at = row.get("created_at")
    scene_type = row.get("scene_type")
    operating_regime = row.get("operating_regime")
    ingest = row.get("ingest") if isinstance(row.get("ingest"), dict) else {}
    source_format = ingest.get("source_format") if isinstance(ingest, dict) else None
    summary = row.get("summary") if isinstance(row.get("summary"), dict) else {}
    has_packed_depth = 1 if bool(summary.get("has_packed_depth")) else 0
    num_devices = int(summary.get("num_devices") or 0)

    row_json = json.dumps(row, default=str)
    indexed_at = float(row.get("indexed_at_unix_s") or _now_s())

    devs = row.get("devices") if isinstance(row.get("devices"), list) else []
    default_device_id = None
    try:
        if devs and isinstance(devs[0], dict):
            default_device_id = str(devs[0].get("device_id") or "") or None
    except Exception:
        default_device_id = None

    conn.execute(
        """
        INSERT INTO bundles(
          bundle_dir, capture_id, created_at, scene_type, operating_regime,
          source_format, has_packed_depth, num_devices, default_device_id,
          teacher_depth_count, teacher_depth_mtime_ns,
          manifest_mtime_ns, manifest_size, indexed_at_unix_s, row_json
        ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
        ON CONFLICT(bundle_dir) DO UPDATE SET
          capture_id=excluded.capture_id,
          created_at=excluded.created_at,
          scene_type=excluded.scene_type,
          operating_regime=excluded.operating_regime,
          source_format=excluded.source_format,
          has_packed_depth=excluded.has_packed_depth,
          num_devices=excluded.num_devices,
          default_device_id=excluded.default_device_id,
          teacher_depth_count=excluded.teacher_depth_count,
          teacher_depth_mtime_ns=excluded.teacher_depth_mtime_ns,
          manifest_mtime_ns=excluded.manifest_mtime_ns,
          manifest_size=excluded.manifest_size,
          indexed_at_unix_s=excluded.indexed_at_unix_s,
          row_json=excluded.row_json;
        """,
        (
            bdir,
            str(capture_id) if capture_id is not None else None,
            str(created_at) if created_at is not None else None,
            str(scene_type) if scene_type is not None else None,
            str(operating_regime) if operating_regime is not None else None,
            str(source_format) if source_format is not None else None,
            int(has_packed_depth),
            int(num_devices),
            str(default_device_id) if default_device_id is not None else None,
            int(teacher_depth_count),
            int(teacher_depth_mtime_ns),
            int(manifest_mtime_ns),
            int(manifest_size),
            float(indexed_at),
            row_json,
        ),
    )

    # Devices table: simple upsert per device
    for d in devs:
        if not isinstance(d, dict):
            continue
        did = str(d.get("device_id") or "")
        if not did:
            continue

        wsum = d.get("waveform_depth_stream_summary")
        idx_path = None
        frames_count = None
        gaps = None
        if isinstance(d.get("waveform_depth_stream"), dict):
            idx_path = d["waveform_depth_stream"].get("index_path")
        if isinstance(wsum, dict) and bool(wsum.get("ok")):
            fr = wsum.get("frames", {}) if isinstance(wsum.get("frames"), dict) else {}
            frames_count = fr.get("count")
            gaps = fr.get("gaps")

        conn.execute(
            """
            INSERT INTO devices(
              bundle_dir, device_id, video_path, video_size_bytes,
              intrinsics_path, timestamps_path,
              packed_depth_index_path, packed_depth_frames_count, packed_depth_gaps
            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
            ON CONFLICT(bundle_dir, device_id) DO UPDATE SET
              video_path=excluded.video_path,
              video_size_bytes=excluded.video_size_bytes,
              intrinsics_path=excluded.intrinsics_path,
              timestamps_path=excluded.timestamps_path,
              packed_depth_index_path=excluded.packed_depth_index_path,
              packed_depth_frames_count=excluded.packed_depth_frames_count,
              packed_depth_gaps=excluded.packed_depth_gaps;
            """,
            (
                bdir,
                did,
                d.get("video_path"),
                d.get("video_path_size_bytes"),
                d.get("intrinsics_path"),
                d.get("timestamps_path"),
                str(idx_path) if idx_path else None,
                int(frames_count) if frames_count is not None else None,
                int(gaps) if gaps is not None else None,
            ),
        )


def build_curation_index_sqlite(
    *,
    captures_root: Path,
    db_path: Path,
    config: Optional[SQLiteIndexConfig] = None,
) -> Dict[str, Any]:
    cfg = config or SQLiteIndexConfig()
    captures_root = Path(captures_root)
    db_path = Path(db_path)
    t0 = _now_s()

    conn = _connect(db_path)
    try:
        _ensure_schema(conn)

        existing = _existing_manifest_stats(conn) if bool(cfg.incremental) else {}

        bundles = _discover_bundles(captures_root, mode=str(cfg.discover))
        to_index = []
        skipped = 0
        for b in bundles:
            mp = Path(b) / "manifest.json"
            try:
                st = mp.stat()
                mtime_ns = int(getattr(st, "st_mtime_ns", int(st.st_mtime * 1e9)))
                size = int(st.st_size)
            except Exception:
                mtime_ns = 0
                size = 0

            td_count, td_mtime_ns = _teacher_depth_stats(Path(b))
            prev = existing.get(str(b))
            if (
                prev
                and int(prev.get("manifest_mtime_ns", -1)) == mtime_ns
                and int(prev.get("manifest_size", -2)) == size
                and int(prev.get("teacher_depth_count", -3)) == int(td_count)
                and int(prev.get("teacher_depth_mtime_ns", -4)) == int(td_mtime_ns)
            ):
                skipped += 1
                continue
            to_index.append((Path(b), mtime_ns, size, int(td_count), int(td_mtime_ns)))

        # Parallel row computation; single-thread DB writes
        curation_cfg = CurationIndexConfig(
            workers=int(cfg.workers),
            include_depth_stream_summary=bool(cfg.include_depth_stream_summary),
            discover=str(cfg.discover),
        )

        # Use the same worker pattern as JSONL indexer via its internal row builder.
        from concurrent.futures import ThreadPoolExecutor, as_completed

        ok = 0
        fail = 0
        conn.execute("BEGIN;")
        with ThreadPoolExecutor(max_workers=max(1, int(cfg.workers))) as ex:
            futs = {
                ex.submit(
                    _bundle_row,
                    bdir,
                    include_depth_stream_summary=bool(curation_cfg.include_depth_stream_summary),
                ): (bdir, mtime_ns, size, td_count, td_mtime_ns)
                for (bdir, mtime_ns, size, td_count, td_mtime_ns) in to_index
            }
            n_written = 0
            for f in as_completed(futs):
                bdir, mtime_ns, size, td_count, td_mtime_ns = futs[f]
                row = f.result()
                try:
                    _upsert_row(
                        conn,
                        row=row,
                        manifest_mtime_ns=mtime_ns,
                        manifest_size=size,
                        teacher_depth_count=int(td_count),
                        teacher_depth_mtime_ns=int(td_mtime_ns),
                    )
                    if bool(row.get("ok")) and not row.get("error"):
                        ok += 1
                    else:
                        fail += 1
                except Exception:
                    fail += 1
                n_written += 1
                # Periodic commit to keep WAL bounded
                if n_written % 200 == 0:
                    conn.execute("COMMIT;")
                    conn.execute("BEGIN;")
        conn.execute("COMMIT;")

        return {
            "captures_root": str(captures_root),
            "db_path": str(db_path),
            "num_bundles_found": int(len(bundles)),
            "num_indexed": int(len(to_index)),
            "num_skipped": int(skipped),
            "ok": int(ok),
            "failed": int(fail),
            "elapsed_s": float(_now_s() - t0),
        }
    finally:
        try:
            conn.close()
        except Exception:
            pass