import pymysql
from datetime import datetime
from indexer.config import DB_CONFIG, BATCH_SIZE


def get_connection():
    return pymysql.connect(**DB_CONFIG)


# ── Run management ──────────────────────────────────────────

def create_run(cur) -> int:
    cur.execute(
        "INSERT INTO runs (started_at, status) VALUES (%s, 'RUNNING')",
        (datetime.now(),)
    )
    return cur.lastrowid


def finalize_run(cur, run_id: int, stats: dict):
    cur.execute(
        """UPDATE runs
           SET finished_at = %s, status = 'COMPLETED',
               files_total = %s, files_new = %s, files_modified = %s,
               files_deleted = %s, files_unchanged = %s
           WHERE id = %s""",
        (datetime.now(), stats["total"], stats["new"], stats["modified"],
         stats["deleted"], stats["unchanged"], run_id)
    )


def fail_run(cur, run_id: int):
    cur.execute(
        "UPDATE runs SET finished_at = %s, status = 'FAILED' WHERE id = %s",
        (datetime.now(), run_id)
    )


# ── Load DB state ──────────────────────────────────────────

def load_all_files(cur) -> dict:
    """
    Načte všechny existující soubory z DB do RAM.
    Returns: {relative_path: {id, size, mtime, content_hash}}
    """
    cur.execute(
        """SELECT id, relative_path, file_size, mtime, content_hash
           FROM files WHERE exists_now = 1"""
    )
    result = {}
    for row in cur.fetchall():
        file_id, rel_path, size, mtime, content_hash = row
        result[rel_path] = {
            "id": file_id,
            "size": size,
            "mtime": mtime,
            "content_hash": content_hash,
        }
    return result


# ── Batch operations ────────────────────────────────────────

def batch_insert_files(cur, files_list: list, run_id: int) -> dict:
    """
    Batch INSERT (or re-activate) souborů.
    Handles re-appearing files that were previously deleted (exists_now=0)
    via ON DUPLICATE KEY UPDATE.
    files_list: [{relative_path, file_name, directory, size, mtime, content_hash}]
    Returns: {relative_path: file_id}
    """
    path_to_id = {}
    for i in range(0, len(files_list), BATCH_SIZE):
        chunk = files_list[i:i + BATCH_SIZE]
        for f in chunk:
            cur.execute(
                """INSERT INTO files
                   (relative_path, file_name, directory, file_size, mtime,
                    content_hash, first_seen_run, last_seen_run, exists_now)
                   VALUES (%s, %s, %s, %s, %s, %s, %s, %s, 1)
                   ON DUPLICATE KEY UPDATE
                    file_name = VALUES(file_name),
                    directory = VALUES(directory),
                    file_size = VALUES(file_size),
                    mtime = VALUES(mtime),
                    content_hash = VALUES(content_hash),
                    last_seen_run = VALUES(last_seen_run),
                    exists_now = 1""",
                (f["relative_path"], f["file_name"], f["directory"],
                 f["size"], f["mtime"], f["content_hash"], run_id, run_id)
            )
        # Fetch real IDs
        paths = [f["relative_path"] for f in chunk]
        placeholders = ",".join(["%s"] * len(paths))
        cur.execute(
            f"SELECT id, relative_path FROM files WHERE relative_path IN ({placeholders})",
            paths,
        )
        for row in cur.fetchall():
            path_to_id[row[1]] = row[0]
    return path_to_id


def batch_update_modified(cur, files_list: list, run_id: int):
    """
    Batch UPDATE změněných souborů.
    files_list: [{id, size, mtime, content_hash}]
    """
    for i in range(0, len(files_list), BATCH_SIZE):
        chunk = files_list[i:i + BATCH_SIZE]
        cur.executemany(
            """UPDATE files
               SET file_size = %s, mtime = %s, content_hash = %s,
                   last_seen_run = %s, exists_now = 1
               WHERE id = %s""",
            [(f["size"], f["mtime"], f["content_hash"], run_id, f["id"])
             for f in chunk]
        )


def batch_mark_deleted(cur, file_ids: list, run_id: int):
    """Batch UPDATE smazaných souborů — exists_now = 0."""
    for i in range(0, len(file_ids), BATCH_SIZE):
        chunk = file_ids[i:i + BATCH_SIZE]
        cur.executemany(
            "UPDATE files SET exists_now = 0, last_seen_run = %s WHERE id = %s",
            [(run_id, fid) for fid in chunk]
        )


def batch_update_unchanged(cur, file_ids: list, run_id: int):
    """Batch UPDATE nezměněných souborů — jen last_seen_run."""
    for i in range(0, len(file_ids), BATCH_SIZE):
        chunk = file_ids[i:i + BATCH_SIZE]
        cur.executemany(
            "UPDATE files SET last_seen_run = %s, exists_now = 1 WHERE id = %s",
            [(run_id, fid) for fid in chunk]
        )