#!/usr/bin/env python3
"""
Migrate data from SQLite to PostgreSQL.

Usage:
    DATABASE_URL=postgresql://ctxd:ctxd_local_dev@localhost:5432/ctxd \
    SQLITE_PATH=/data/ctxd.db \
    python3 -m ctxd.migrate_sqlite_to_pg

Or inside the Docker container:
    docker exec dossier python3 -m ctxd.migrate_sqlite_to_pg

Environment variables:
    DATABASE_URL  — PostgreSQL connection string (required)
    SQLITE_PATH   — Path to SQLite DB file (default: /data/ctxd.db)
"""
import os
import sqlite3
import sys

try:
    import psycopg
    from psycopg.rows import dict_row
except ImportError:
    print("ERROR: psycopg is required. Install with: pip install psycopg[binary]")
    sys.exit(1)


SQLITE_PATH = os.environ.get("SQLITE_PATH", "/data/ctxd.db")
PG_URL = os.environ.get("DATABASE_URL", "")

# Tables in migration order (parents before children for FK safety)
TABLES = [
    "users",
    "projects",
    "project_permissions",
    "project_context",
    "context_files",
    "user_profiles",
    "user_workspaces",
    "workspace_files",
    "change_requests",
    "reviews",
    "snapshots",
    "audit_log",
]

# Columns that need type conversion from SQLite INTEGER to PostgreSQL BOOLEAN
BOOL_COLUMNS = {
    "users": ["active"],
    "projects": ["auto_sync"],
}


def migrate():
    if not PG_URL:
        print("ERROR: DATABASE_URL environment variable not set")
        print("Example: DATABASE_URL=postgresql://ctxd:ctxd_local_dev@localhost:5432/ctxd")
        sys.exit(1)

    if not os.path.exists(SQLITE_PATH):
        print(f"ERROR: SQLite database not found at {SQLITE_PATH}")
        sys.exit(1)

    print(f"Migrating from SQLite ({SQLITE_PATH}) to PostgreSQL ({PG_URL})")
    print()

    # Connect to SQLite
    sconn = sqlite3.connect(SQLITE_PATH)
    sconn.row_factory = sqlite3.Row

    # Connect to PostgreSQL
    pconn = psycopg.connect(PG_URL, row_factory=dict_row)
    pconn.autocommit = False

    # Step 1: Clear all data from PostgreSQL tables
    print("Clearing existing PostgreSQL data...")
    pconn.execute(
        "TRUNCATE TABLE fts_context, audit_log, reviews, change_requests, "
        "workspace_files, user_workspaces, context_files, project_context, "
        "snapshots, user_profiles, project_permissions, projects, users CASCADE"
    )
    pconn.commit()
    print("  Done.")
    print()

    # Step 2: Migrate each table
    total_rows = 0
    for table in TABLES:
        # Get column names from SQLite
        try:
            cur = sconn.execute(f"PRAGMA table_info({table})")
            columns = [row["name"] for row in cur.fetchall()]
        except sqlite3.OperationalError:
            print(f"  {table}: table not found in SQLite, skipping")
            continue

        if not columns:
            print(f"  {table}: no columns found, skipping")
            continue

        # Read all rows from SQLite
        col_str = ", ".join(columns)
        try:
            cur = sconn.execute(f"SELECT {col_str} FROM {table}")
            rows = cur.fetchall()
        except sqlite3.OperationalError:
            print(f"  {table}: error reading from SQLite, skipping")
            continue

        if not rows:
            print(f"  {table}: 0 rows")
            continue

        # Insert into PostgreSQL
        val_str = ", ".join(["%s"] * len(columns))
        insert_sql = f'INSERT INTO {table} ({col_str}) VALUES ({val_str}) ON CONFLICT DO NOTHING'

        bool_cols = BOOL_COLUMNS.get(table, [])
        count = 0

        for row in rows:
            values = []
            for col in columns:
                val = row[col]
                # Convert integer 0/1 to boolean for PostgreSQL BOOLEAN columns
                if col in bool_cols and val is not None:
                    val = bool(val)
                values.append(val)
            try:
                pconn.execute(insert_sql, values)
                count += 1
            except Exception as fk_err:
                # Skip rows with FK violations (e.g. orphaned snapshots)
                pconn.rollback()
                count_skipped = count_skipped + 1 if 'count_skipped' in dir() else 1
                continue

        pconn.commit()
        total_rows += count
        print(f"  {table}: {count} rows migrated")

    # Step 3: Rebuild FTS index
    print()
    print("Rebuilding FTS index...")
    pconn.execute("DELETE FROM fts_context")
    pconn.commit()

    # Re-populate FTS from source tables
    pconn.execute("""
        INSERT INTO fts_context (source_id, content, project_id, file_path, source_type, tsv)
        SELECT project_id, content, project_id, 'context.md', 'project_context',
               to_tsvector('english', content)
        FROM project_context
        WHERE content != ''
    """)
    fts_pc = pconn.cursor().rowcount

    pconn.execute("""
        INSERT INTO fts_context (source_id, content, project_id, file_path, source_type, tsv)
        SELECT file_id::text, content, project_id, file_path, 'context_file',
               to_tsvector('english', content)
        FROM context_files
        WHERE content != ''
    """)
    fts_cf = pconn.cursor().rowcount

    pconn.execute("""
        INSERT INTO fts_context (source_id, content, project_id, file_path, source_type, tsv)
        SELECT user_id, content, '~user', user_id, 'user_profile',
               to_tsvector('english', content)
        FROM user_profiles
        WHERE content != ''
    """)
    fts_up = pconn.cursor().rowcount

    pconn.commit()
    print(f"  project_context: {fts_pc} entries")
    print(f"  context_files: {fts_cf} entries")
    print(f"  user_profiles: {fts_up} entries")

    # Step 4: Reset SERIAL sequences to max(existing_id) + 1
    print()
    print("Resetting SERIAL sequences...")
    for table, col in [
        ("audit_log", "entry_id"),
        ("context_files", "file_id"),
        ("project_permissions", "id"),
        ("reviews", "review_id"),
        ("workspace_files", "file_id"),
    ]:
        try:
            pconn.execute(f"SELECT setval(pg_get_serial_sequence('{table}', '{col}'), COALESCE((SELECT MAX({col}) FROM {table}), 1))")
            print(f"  {table}.{col}: seq reset")
        except Exception as e:
            print(f"  {table}.{col}: skipped ({e})")
    pconn.commit()

    print()
    print("=" * 60)
    print(f"Migration complete! {total_rows} total rows migrated.")
    print("=" * 60)

    sconn.close()
    pconn.close()


if __name__ == "__main__":
    migrate()