from __future__ import annotations

import sqlite3

from .connection import connect, resolve_db_path
from .schema import ACCOUNT_ADDITIVE_COLUMNS, SCHEMA_SQL, SCHEMA_VERSION, TRANSACTION_ADDITIVE_COLUMNS

def _existing_columns(conn: sqlite3.Connection, table: str) -> set[str]:
    return {row["name"] for row in conn.execute(f"PRAGMA table_info({table})")}


def _add_missing_columns(conn: sqlite3.Connection, table: str, columns: dict[str, str]) -> None:
    existing = _existing_columns(conn, table)
    for name, definition in columns.items():
        if name not in existing:
            conn.execute(f"ALTER TABLE {table} ADD COLUMN {name} {definition}")


def migrate_db(conn: sqlite3.Connection) -> None:
    """Apply additive, idempotent migrations only."""
    _add_missing_columns(conn, "accounts", ACCOUNT_ADDITIVE_COLUMNS)
    _add_missing_columns(conn, "transactions", TRANSACTION_ADDITIVE_COLUMNS)
    conn.execute("CREATE INDEX IF NOT EXISTS idx_transactions_datetime ON transactions(transaction_datetime)")
    conn.execute("""CREATE TABLE IF NOT EXISTS category_rules (
        id TEXT PRIMARY KEY,
        priority INTEGER NOT NULL DEFAULT 100,
        match_field TEXT NOT NULL,
        match_type TEXT NOT NULL DEFAULT 'contains',
        pattern TEXT NOT NULL,
        amount_min INTEGER,
        amount_max INTEGER,
        day_of_month INTEGER,
        transaction_type TEXT NOT NULL DEFAULT '',
        category TEXT NOT NULL,
        subcategory TEXT NOT NULL DEFAULT '',
        person TEXT NOT NULL DEFAULT '',
        is_fixed INTEGER,
        confidence REAL NOT NULL DEFAULT 1.0,
        active INTEGER NOT NULL DEFAULT 1,
        memo TEXT NOT NULL DEFAULT '',
        created_at TEXT NOT NULL,
        updated_at TEXT NOT NULL
    )""")
    _add_missing_columns(conn, "category_rules", {"amount_min": "INTEGER", "amount_max": "INTEGER", "day_of_month": "INTEGER"})
    conn.execute("CREATE INDEX IF NOT EXISTS idx_category_rules_active_priority ON category_rules(active, priority)")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_category_rules_unique ON category_rules(match_field, match_type, pattern, transaction_type, category, subcategory, person)")
    conn.execute("""CREATE TABLE IF NOT EXISTS ledger_categories (
        id TEXT PRIMARY KEY,
        category TEXT NOT NULL,
        subcategory TEXT NOT NULL DEFAULT '',
        cashflow_kind TEXT NOT NULL DEFAULT 'expense',
        active INTEGER NOT NULL DEFAULT 1,
        sort_order INTEGER NOT NULL DEFAULT 100,
        memo TEXT NOT NULL DEFAULT '',
        created_at TEXT NOT NULL,
        updated_at TEXT NOT NULL
    )""")
    _add_missing_columns(conn, "ledger_categories", {"cashflow_kind": "TEXT NOT NULL DEFAULT 'expense'"})
    conn.execute("CREATE INDEX IF NOT EXISTS idx_ledger_categories_active_sort ON ledger_categories(active, sort_order, category, subcategory)")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_ledger_categories_unique ON ledger_categories(category, subcategory)")
    conn.execute("""CREATE TABLE IF NOT EXISTS manual_assets (
        id TEXT PRIMARY KEY,
        name TEXT NOT NULL,
        liquidity_bucket TEXT NOT NULL DEFAULT 'other',
        valuation_amount INTEGER,
        valuation_date TEXT NOT NULL DEFAULT '',
        currency TEXT NOT NULL DEFAULT 'KRW',
        source_note TEXT NOT NULL DEFAULT '',
        memo TEXT NOT NULL DEFAULT '',
        active INTEGER NOT NULL DEFAULT 1,
        created_at TEXT NOT NULL,
        updated_at TEXT NOT NULL
    )""")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_manual_assets_active_bucket ON manual_assets(active, liquidity_bucket, name)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_manual_assets_valuation_date ON manual_assets(valuation_date)")
    conn.execute("""CREATE TABLE IF NOT EXISTS asset_snapshots (
        id TEXT PRIMARY KEY,
        basis_date TEXT NOT NULL,
        source_type TEXT NOT NULL,
        source_id TEXT NOT NULL DEFAULT '',
        name TEXT NOT NULL,
        amount INTEGER,
        currency TEXT NOT NULL DEFAULT 'KRW',
        liquidity_bucket TEXT NOT NULL DEFAULT 'other',
        valuation_source TEXT NOT NULL DEFAULT '',
        source_note TEXT NOT NULL DEFAULT '',
        memo TEXT NOT NULL DEFAULT '',
        snapshot_run_id TEXT NOT NULL DEFAULT '',
        correction_of_run_id TEXT NOT NULL DEFAULT '',
        correction_reason TEXT NOT NULL DEFAULT '',
        is_correction INTEGER NOT NULL DEFAULT 0,
        closed_at TEXT NOT NULL DEFAULT '',
        created_at TEXT NOT NULL
    )""")
    _add_missing_columns(conn, "asset_snapshots", {
        "snapshot_run_id": "TEXT NOT NULL DEFAULT ''",
        "correction_of_run_id": "TEXT NOT NULL DEFAULT ''",
        "correction_reason": "TEXT NOT NULL DEFAULT ''",
        "is_correction": "INTEGER NOT NULL DEFAULT 0",
        "closed_at": "TEXT NOT NULL DEFAULT ''",
        "valuation_id": "TEXT NOT NULL DEFAULT ''",
        "selection_policy": "TEXT NOT NULL DEFAULT 'exact'",
        "verification_status": "TEXT NOT NULL DEFAULT 'unverified'",
        "evidence_kind": "TEXT NOT NULL DEFAULT 'applied'",
        "exclusion_reason": "TEXT NOT NULL DEFAULT ''",
    })
    conn.execute("CREATE INDEX IF NOT EXISTS idx_asset_snapshots_basis_date ON asset_snapshots(basis_date)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_asset_snapshots_source ON asset_snapshots(source_type, source_id)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_asset_snapshots_run ON asset_snapshots(basis_date, snapshot_run_id, created_at)")
    conn.execute("""CREATE TABLE IF NOT EXISTS asset_snapshot_runs (
        id TEXT PRIMARY KEY, basis_date TEXT NOT NULL, close_status TEXT NOT NULL,
        selection_policy TEXT NOT NULL DEFAULT 'exact', idempotency_key TEXT NOT NULL DEFAULT '',
        approved_by TEXT NOT NULL DEFAULT '', approved_at TEXT NOT NULL DEFAULT '',
        approval_reason TEXT NOT NULL DEFAULT '', approval_reference TEXT NOT NULL DEFAULT '',
        correction_of_run_id TEXT NOT NULL DEFAULT '', correction_reason TEXT NOT NULL DEFAULT '',
        applied_evidence TEXT NOT NULL DEFAULT '[]', excluded_evidence TEXT NOT NULL DEFAULT '[]',
        carried_evidence TEXT NOT NULL DEFAULT '[]', request_fingerprint TEXT NOT NULL DEFAULT '', created_at TEXT NOT NULL
    )""")
    _add_missing_columns(conn, "asset_snapshot_runs", {"request_fingerprint": "TEXT NOT NULL DEFAULT ''"})
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_asset_snapshot_runs_idempotency ON asset_snapshot_runs(idempotency_key) WHERE idempotency_key <> ''")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_asset_snapshot_runs_initial_basis ON asset_snapshot_runs(basis_date) WHERE correction_of_run_id = ''")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_asset_snapshot_runs_correction_parent ON asset_snapshot_runs(correction_of_run_id) WHERE correction_of_run_id <> ''")
    conn.execute("""CREATE TABLE IF NOT EXISTS review_decisions (
        id TEXT PRIMARY KEY,
        target_type TEXT NOT NULL,
        target_id TEXT NOT NULL,
        status TEXT NOT NULL DEFAULT 'pending',
        decision_type TEXT NOT NULL DEFAULT 'unknown',
        reason_code TEXT NOT NULL DEFAULT '',
        memo TEXT NOT NULL DEFAULT '',
        operator TEXT NOT NULL DEFAULT 'operator',
        decided_at TEXT NOT NULL DEFAULT '',
        review_after TEXT NOT NULL DEFAULT '',
        target_payload TEXT NOT NULL DEFAULT '{}',
        created_at TEXT NOT NULL,
        updated_at TEXT NOT NULL
    )""")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_review_decisions_target ON review_decisions(target_type, target_id, updated_at)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_review_decisions_status ON review_decisions(status, review_after, updated_at)")
    conn.execute("""CREATE TABLE IF NOT EXISTS reconciliation_sessions (
        id TEXT PRIMARY KEY,
        account_id TEXT NOT NULL,
        basis_date TEXT NOT NULL,
        expected_balance INTEGER,
        actual_balance INTEGER,
        difference INTEGER,
        status TEXT NOT NULL DEFAULT 'open',
        closed_at TEXT NOT NULL DEFAULT '',
        source_note TEXT NOT NULL DEFAULT '',
        memo TEXT NOT NULL DEFAULT '',
        operator TEXT NOT NULL DEFAULT 'operator',
        created_at TEXT NOT NULL,
        updated_at TEXT NOT NULL
    )""")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_reconciliation_sessions_account_basis ON reconciliation_sessions(account_id, basis_date)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_reconciliation_sessions_status ON reconciliation_sessions(status, closed_at)")
    conn.execute("""CREATE TABLE IF NOT EXISTS account_valuations (
        id TEXT PRIMARY KEY, account_id TEXT NOT NULL REFERENCES accounts(id), basis_date TEXT NOT NULL,
        amount INTEGER NOT NULL, currency TEXT NOT NULL DEFAULT 'KRW', valuation_kind TEXT NOT NULL DEFAULT 'balance',
        source_type TEXT NOT NULL DEFAULT 'manual', source_ref TEXT NOT NULL DEFAULT '',
        verification_status TEXT NOT NULL DEFAULT 'unverified', recorded_at TEXT NOT NULL,
        memo TEXT NOT NULL DEFAULT '', idempotency_key TEXT NOT NULL DEFAULT '',
        supersedes_id TEXT REFERENCES account_valuations(id), correction_reason TEXT NOT NULL DEFAULT '',
        as_of_at TEXT, timezone TEXT, cost_basis INTEGER, net_contributed INTEGER,
        reported_principal_kind TEXT, reported_principal_label TEXT, profit INTEGER,
        return_rate REAL, return_basis TEXT, principal INTEGER, interest INTEGER, fee INTEGER,
        representative_liability_definition TEXT
    )""")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_account_valuations_account_date ON account_valuations(account_id, basis_date, recorded_at)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_account_valuations_status_date ON account_valuations(verification_status, basis_date)")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_account_valuations_idempotency ON account_valuations(account_id, idempotency_key) WHERE idempotency_key <> ''")
    conn.execute("CREATE UNIQUE INDEX IF NOT EXISTS idx_account_valuations_single_correction ON account_valuations(supersedes_id) WHERE supersedes_id IS NOT NULL")
    conn.execute("INSERT OR REPLACE INTO schema_meta(key, value) VALUES ('schema_version', ?)", (SCHEMA_VERSION,))


def init_db(db_path: str | None = None) -> str:
    path = resolve_db_path(db_path)
    with connect(str(path)) as conn:
        conn.executescript(SCHEMA_SQL)
        migrate_db(conn)
    return str(path)