"""Additive legacy SQLite migration. Never rewrites existing order numbers."""
import sqlite3
from datetime import datetime
from decimal import Decimal, ROUND_HALF_UP
from pathlib import Path


def upgrade_database(path):
    path = Path(path)
    if not path.exists():
        return
    with sqlite3.connect(path) as con:
        tables = {r[0] for r in con.execute("SELECT name FROM sqlite_master WHERE type='table'")}
        if 'orders' not in tables:
            return
        version = con.execute('PRAGMA user_version').fetchone()[0]
        if version >= 4:
            return
        duplicates = con.execute('SELECT order_no, COUNT(*) FROM orders GROUP BY order_no HAVING COUNT(*) > 1').fetchall()
        if duplicates:
            raise RuntimeError('升级前请处理重复单号（原数据未修改）：%s' % duplicates)
        backup = path.with_name(path.name + '.pre-upgrade-' + datetime.now().strftime('%Y%m%d-%H%M%S-%f') + '.bak')
        with sqlite3.connect(backup) as dest:
            con.backup(dest)
        con.execute('BEGIN IMMEDIATE')
        try:
            if version < 2:
                upgrade_fixed_amounts(con)
            if version < 3:
                merge_approval(con, tables)
            add_tracking(con)
            con.execute('PRAGMA user_version=4')
            con.commit()
        except Exception:
            con.rollback()
            raise


def add_tracking(con):
    # Historical invoices, payments and deliveries are unknown until recorded.
    additions = {
        'needs_prepayment': 'BOOLEAN NOT NULL DEFAULT 0',
        'invoice_status': "VARCHAR(20) NOT NULL DEFAULT 'unknown'",
        'delivery_status': "VARCHAR(20) NOT NULL DEFAULT 'unknown'",
        'payment_status': "VARCHAR(20) NOT NULL DEFAULT 'unknown'",
        'payment_date': "VARCHAR(10) NOT NULL DEFAULT ''",
        'fulfillment_note': "TEXT NOT NULL DEFAULT ''",
        'payment_note': "TEXT NOT NULL DEFAULT ''",
        'fulfillment_revision': 'INTEGER NOT NULL DEFAULT -1',
        'payment_revision': 'INTEGER NOT NULL DEFAULT -1',
    }
    existing = {row[1] for row in con.execute('PRAGMA table_info(orders)')}
    for name, definition in additions.items():
        if name not in existing:
            con.execute('ALTER TABLE orders ADD COLUMN %s %s' % (name, definition))


def upgrade_fixed_amounts(con):
    additions = {
        'users': {'session_version': 'INTEGER NOT NULL DEFAULT 1', 'must_change_password': 'BOOLEAN NOT NULL DEFAULT 1'},
        'orders': {'reviewed_by_id': 'INTEGER', 'approved_by_id': 'INTEGER', 'revision': 'INTEGER NOT NULL DEFAULT 0', 'row_version': 'INTEGER NOT NULL DEFAULT 1'},
        'approval_logs': {'user_id': 'INTEGER', 'revision': 'INTEGER NOT NULL DEFAULT 0', 'from_status': 'VARCHAR(20)', 'to_status': 'VARCHAR(20)'},
    }
    for table, columns in additions.items():
        existing = {r[1] for r in con.execute('PRAGMA table_info(%s)' % table)}
        for name, definition in columns.items():
            if name not in existing:
                con.execute('ALTER TABLE %s ADD COLUMN %s %s' % (table, name, definition))
    for table, old, new, places in [
        ('materials', 'price', 'price_units', 4), ('orders', 'total_amount', 'total_cents', 2),
        ('order_items', 'qty', 'qty_units', 4), ('order_items', 'price', 'price_units', 4),
        ('order_items', 'amount', 'amount_cents', 2),
    ]:
        columns = {r[1] for r in con.execute('PRAGMA table_info(%s)' % table)}
        if new in columns:
            continue
        con.execute('ALTER TABLE %s ADD COLUMN %s INTEGER DEFAULT 0' % (table, new))
        for row_id, value in con.execute('SELECT id, %s FROM %s' % (old, table)).fetchall():
            val = Decimal(str(value or 0))
            if not val.is_finite() or abs(val) * 10 ** places > 2 ** 63 - 1:
                raise RuntimeError('无法迁移 %s.id=%s 的金额/数量，请检查原始数据' % (table, row_id))
            scaled = int((val * 10 ** places).quantize(Decimal('1'), rounding=ROUND_HALF_UP))
            con.execute('UPDATE %s SET %s=? WHERE id=?' % (table, new), (scaled, row_id))
    con.execute('CREATE UNIQUE INDEX IF NOT EXISTS uq_orders_order_no ON orders(order_no)')


def merge_approval(con, tables):
    # Check queued tasks against the OLD status before consolidating stages.
    # Completed deliveries/logs and archived PDF bytes must remain untouched.
    if 'notifications' in tables:
        con.execute("""UPDATE notifications SET status='cancelled',
            last_error='审批流程已合并，旧通知已失效', lease_token=NULL, lease_until=NULL
            WHERE channel IN ('review','approval') AND status IN ('pending','retry','sending','failed')
            AND NOT EXISTS (SELECT 1 FROM orders o WHERE o.id=notifications.order_id
                AND o.status=notifications.expected_status AND o.revision=notifications.revision
                AND o.status IN ('pending_review','pending_approval'))""")
        con.execute("""UPDATE notifications SET channel='approval', expected_status='pending_approval',
            event='待审批（流程已合并）' WHERE channel IN ('review','approval')
            AND status IN ('pending','retry','sending','failed')""")
    if 'notification_settings' in tables:
        con.execute("""UPDATE notification_settings SET approval_webhook=
            CASE WHEN COALESCE(approval_webhook,'')='' THEN COALESCE(review_webhook,'')
            ELSE approval_webhook END, review_webhook=''""")
    con.execute("""UPDATE orders SET status='pending_approval', row_version=row_version+1
        WHERE status IN ('pending_review','pending_approval')""")
    con.execute("""UPDATE users SET role='approver', session_version=session_version+1
        WHERE role='reviewer'""")