"""Database connection management and schema initialisation."""
from __future__ import annotations

import os
import sqlite3
from contextlib import asynccontextmanager
from pathlib import Path
from typing import AsyncGenerator

import aiosqlite

DB_PATH: str = os.getenv("DB_PATH", "data/tracker.db")

_DDL = """
CREATE TABLE IF NOT EXISTS runs (
    id             INTEGER PRIMARY KEY AUTOINCREMENT,
    created_at     TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
    scenario       TEXT    NOT NULL,
    identifier     TEXT    NOT NULL,
    success        INTEGER NOT NULL,
    failure_reason TEXT,
    steps_json     TEXT    NOT NULL DEFAULT '[]',
    total_ms       INTEGER NOT NULL DEFAULT 0
);

CREATE INDEX IF NOT EXISTS idx_runs_scenario   ON runs(scenario);
CREATE INDEX IF NOT EXISTS idx_runs_created_at ON runs(created_at);
CREATE INDEX IF NOT EXISTS idx_runs_identifier ON runs(identifier);

CREATE TABLE IF NOT EXISTS flow_configs (
    id                          INTEGER PRIMARY KEY AUTOINCREMENT,
    created_at                  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
    name                        TEXT    NOT NULL,
    is_active                   INTEGER NOT NULL DEFAULT 0,
    search_texts_json           TEXT    NOT NULL DEFAULT '[]',
    search_box_selector         TEXT    NOT NULL DEFAULT '',
    search_box_selector_type    TEXT    NOT NULL DEFAULT 'css',
    search_submit_selector      TEXT    NOT NULL DEFAULT '',
    search_submit_selector_type TEXT    NOT NULL DEFAULT 'css',
    search_results_selector      TEXT    NOT NULL DEFAULT '',
    search_results_selector_type TEXT    NOT NULL DEFAULT 'css',
    scroll_container_selector      TEXT    NOT NULL DEFAULT '',
    scroll_container_selector_type TEXT    NOT NULL DEFAULT 'css',
    max_scrolls                 INTEGER NOT NULL DEFAULT 30,
    scroll_pause_ms             INTEGER NOT NULL DEFAULT 1200,
    no_new_content_timeout_ms   INTEGER NOT NULL DEFAULT 3000,
    pagination_selector         TEXT    NOT NULL DEFAULT '',
    pagination_selector_type    TEXT    NOT NULL DEFAULT 'css',
    max_pages                   INTEGER NOT NULL DEFAULT 10,
    pagination_wait_ms          INTEGER NOT NULL DEFAULT 1500,
    item_selector_template      TEXT    NOT NULL DEFAULT '',
    item_selector_type          TEXT    NOT NULL DEFAULT 'css',
    item_url_template           TEXT    NOT NULL DEFAULT '',
    target_item_ids_json        TEXT    NOT NULL DEFAULT '[]',
    target_url                  TEXT    NOT NULL DEFAULT ''
);

CREATE TABLE IF NOT EXISTS batch_runs (
    id          INTEGER PRIMARY KEY AUTOINCREMENT,
    batch_id    TEXT    NOT NULL UNIQUE,
    config_id   INTEGER,
    config_name TEXT    NOT NULL DEFAULT '',
    workers     INTEGER NOT NULL DEFAULT 1,
    total_runs  INTEGER NOT NULL DEFAULT 0,
    stagger_ms  INTEGER NOT NULL DEFAULT 0,
    headless    INTEGER NOT NULL DEFAULT 1,
    started_at  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
    finished_at TEXT,
    succeeded   INTEGER NOT NULL DEFAULT 0,
    failed      INTEGER NOT NULL DEFAULT 0,
    stopped     INTEGER NOT NULL DEFAULT 0,
    error       TEXT
);
"""


def init_db() -> None:
    """Create the DB file and apply the schema (sync, called once at startup)."""
    path = Path(DB_PATH)
    path.parent.mkdir(parents=True, exist_ok=True)
    conn = sqlite3.connect(str(path))
    conn.executescript(_DDL)
    # Additive migrations for columns added after initial release
    _migrate(conn)
    conn.commit()
    conn.close()


def _migrate(conn: sqlite3.Connection) -> None:
    existing = {row[1] for row in conn.execute("PRAGMA table_info(flow_configs)")}
    additions = {
        "search_results_selector_type": "TEXT NOT NULL DEFAULT 'css'",
        "item_url_template": "TEXT NOT NULL DEFAULT ''",
        "scroll_container_selector_type": "TEXT NOT NULL DEFAULT 'css'",
        "pagination_selector": "TEXT NOT NULL DEFAULT ''",
        "pagination_selector_type": "TEXT NOT NULL DEFAULT 'css'",
        "max_pages": "INTEGER NOT NULL DEFAULT 10",
        "pagination_wait_ms": "INTEGER NOT NULL DEFAULT 1500",
        "target_url": "TEXT NOT NULL DEFAULT ''",
        "scenario":   "TEXT NOT NULL DEFAULT 'dynamic'",
    }
    for col, definition in additions.items():
        if col not in existing:
            conn.execute(f"ALTER TABLE flow_configs ADD COLUMN {col} {definition}")


@asynccontextmanager
async def get_db() -> AsyncGenerator[aiosqlite.Connection, None]:
    """Async context manager — yields an open, Row-factory-enabled connection."""
    async with aiosqlite.connect(DB_PATH) as db:
        db.row_factory = aiosqlite.Row
        yield db