using LinqToDB.Data;

namespace Azaion.Missions.Database;

// Forward-only migrator. Two SQL blocks run on every container start, in order:
//
//   1. RenameAndDropSql -- idempotent ALTERs that bring a legacy `flights`-era
//      schema up to the renamed `missions` schema, plus DROPs for the
//      GPS-Denied tables (Jira AZ-EPIC B7 / B9). On a fresh DB or an
//      already-migrated DB this block is a no-op (every statement guards on
//      IF EXISTS / column existence).
//
//   2. InitSql -- CREATE TABLE IF NOT EXISTS for the post-migration schema.
//      On a legacy DB the renames in (1) leave tables already present; this
//      block is a no-op for them. On a fresh-install device this block IS
//      the schema. On an already-migrated DB it is a no-op.
//
// Re-running the migrator on any DB state above produces no errors and no
// changes -- this is the suite's "idempotent forward-only" convention.
public static class DatabaseMigrator
{
    public static void Migrate(AppDataConnection db)
    {
        db.Execute(RenameAndDropSql);
        db.Execute(InitSql);
    }

    // Bring legacy `flights` / `aircrafts` schemas up to the renamed shape.
    // Safe to re-run on any DB state.
    private const string RenameAndDropSql = """
        ALTER TABLE IF EXISTS aircrafts RENAME TO vehicles;
        ALTER TABLE IF EXISTS flights   RENAME TO missions;

        DO $$
        BEGIN
            IF EXISTS (SELECT 1 FROM information_schema.columns
                       WHERE table_name = 'missions' AND column_name = 'aircraft_id') THEN
                ALTER TABLE missions RENAME COLUMN aircraft_id TO vehicle_id;
            END IF;
            IF EXISTS (SELECT 1 FROM information_schema.columns
                       WHERE table_name = 'waypoints' AND column_name = 'flight_id') THEN
                ALTER TABLE waypoints RENAME COLUMN flight_id TO mission_id;
            END IF;
            IF EXISTS (SELECT 1 FROM information_schema.columns
                       WHERE table_name = 'map_objects' AND column_name = 'flight_id') THEN
                ALTER TABLE map_objects RENAME COLUMN flight_id TO mission_id;
            END IF;
        END $$;

        ALTER INDEX IF EXISTS ix_flights_aircraft_id RENAME TO ix_missions_vehicle_id;
        ALTER INDEX IF EXISTS ix_waypoints_flight_id RENAME TO ix_waypoints_mission_id;
        ALTER INDEX IF EXISTS ix_map_objects_flight_id RENAME TO ix_map_objects_mission_id;

        DROP TABLE IF EXISTS orthophotos;
        DROP TABLE IF EXISTS gps_corrections;
        """;

    // Post-migration schema. CREATE TABLE IF NOT EXISTS is the idempotent path
    // for fresh DBs; on already-migrated DBs every statement here is a no-op.
    private const string InitSql = """
        CREATE TABLE IF NOT EXISTS vehicles (
            id UUID PRIMARY KEY,
            type INTEGER NOT NULL DEFAULT 0,
            model TEXT NOT NULL,
            name TEXT NOT NULL,
            fuel_type INTEGER NOT NULL DEFAULT 0,
            battery_capacity NUMERIC NOT NULL DEFAULT 0,
            engine_consumption NUMERIC NOT NULL DEFAULT 0,
            engine_consumption_idle NUMERIC NOT NULL DEFAULT 0,
            is_default BOOLEAN NOT NULL DEFAULT FALSE
        );

        CREATE TABLE IF NOT EXISTS missions (
            id UUID PRIMARY KEY,
            created_date TIMESTAMP NOT NULL DEFAULT NOW(),
            name TEXT NOT NULL,
            vehicle_id UUID NOT NULL REFERENCES vehicles(id)
        );

        CREATE TABLE IF NOT EXISTS waypoints (
            id UUID PRIMARY KEY,
            mission_id UUID NOT NULL REFERENCES missions(id),
            lat NUMERIC,
            lon NUMERIC,
            mgrs TEXT,
            waypoint_source INTEGER NOT NULL DEFAULT 0,
            waypoint_objective INTEGER NOT NULL DEFAULT 0,
            order_num INTEGER NOT NULL DEFAULT 0,
            height NUMERIC NOT NULL DEFAULT 0
        );

        CREATE TABLE IF NOT EXISTS map_objects (
            id UUID PRIMARY KEY,
            mission_id UUID NOT NULL REFERENCES missions(id),
            h3_index TEXT NOT NULL,
            mgrs TEXT NOT NULL,
            lat NUMERIC,
            lon NUMERIC,
            class_num INTEGER NOT NULL DEFAULT 0,
            label TEXT NOT NULL DEFAULT '',
            size_width_m NUMERIC NOT NULL DEFAULT 0,
            size_length_m NUMERIC NOT NULL DEFAULT 0,
            confidence NUMERIC NOT NULL DEFAULT 0,
            object_status INTEGER NOT NULL DEFAULT 0,
            first_seen_at TIMESTAMP NOT NULL DEFAULT NOW(),
            last_seen_at TIMESTAMP NOT NULL DEFAULT NOW()
        );

        CREATE INDEX IF NOT EXISTS ix_missions_vehicle_id ON missions(vehicle_id);
        CREATE INDEX IF NOT EXISTS ix_waypoints_mission_id ON waypoints(mission_id);
        CREATE INDEX IF NOT EXISTS ix_map_objects_mission_id ON map_objects(mission_id);

        -- B12 (Option A): exactly-one-default vehicle is enforced by a partial
        -- unique index. Only rows with is_default = true are indexed; two such
        -- rows would conflict. Existing 0-default and 1-default DBs are valid.
        CREATE UNIQUE INDEX IF NOT EXISTS ux_vehicles_one_default
            ON vehicles (is_default) WHERE is_default = TRUE;
        """;
}