use sea_orm_migration::prelude::*;

#[derive(DeriveMigrationName)]
pub struct Migration;

#[async_trait::async_trait]
impl MigrationTrait for Migration {
    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
        // 1. Create task_runs table
        manager
            .create_table(
                Table::create()
                    .table(TaskRuns::Table)
                    .if_not_exists()
                    .col(ColumnDef::new(TaskRuns::Id).uuid().not_null().primary_key())
                    .col(ColumnDef::new(TaskRuns::TaskId).uuid().not_null())
                    .col(ColumnDef::new(TaskRuns::Status).string().not_null())
                    .col(ColumnDef::new(TaskRuns::Logs).text().not_null())
                    .col(ColumnDef::new(TaskRuns::Answer).text().null())
                    .col(
                        ColumnDef::new(TaskRuns::CreatedAt)
                            .timestamp_with_time_zone()
                            .not_null(),
                    )
                    .foreign_key(
                        ForeignKey::create()
                            .name("fk-task_runs-task_id")
                            .from(TaskRuns::Table, TaskRuns::TaskId)
                            .to(Tasks::Table, Tasks::Id)
                            .on_delete(ForeignKeyAction::Cascade),
                    )
                    .to_owned(),
            )
            .await?;

        // 2. Migrate existing data from tasks to task_runs
        // We use raw SQL for simplicity in migration
        let db = manager.get_connection();
        db.execute_unprepared(
            "INSERT INTO task_runs (id, task_id, status, logs, answer, created_at)
             SELECT id, id, status, logs, answer, created_at FROM tasks",
        )
        .await?;

        // 3. Remove columns from tasks table (using a temp table for wider SQLite compatibility if needed,
        // but let's try alter table first as it's cleaner if supported)
        manager
            .alter_table(
                Table::alter()
                    .table(Tasks::Table)
                    .drop_column(Tasks::Status)
                    .drop_column(Tasks::Logs)
                    .drop_column(Tasks::Answer)
                    .to_owned(),
            )
            .await?;

        Ok(())
    }

    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
        // Re-add columns to tasks
        manager
            .alter_table(
                Table::alter()
                    .table(Tasks::Table)
                    .add_column(ColumnDef::new(Tasks::Status).string().null())
                    .add_column(ColumnDef::new(Tasks::Logs).text().null())
                    .add_column(ColumnDef::new(Tasks::Answer).text().null())
                    .to_owned(),
            )
            .await?;

        // Restore data from latest run if possible (best effort)
        let db = manager.get_connection();
        db.execute_unprepared(
            "UPDATE tasks SET 
                status = (SELECT status FROM task_runs WHERE task_id = tasks.id ORDER BY created_at DESC LIMIT 1),
                logs = (SELECT logs FROM task_runs WHERE task_id = tasks.id ORDER BY created_at DESC LIMIT 1),
                answer = (SELECT answer FROM task_runs WHERE task_id = tasks.id ORDER BY created_at DESC LIMIT 1)"
        ).await?;

        manager
            .drop_table(Table::drop().table(TaskRuns::Table).to_owned())
            .await
    }
}

#[derive(DeriveIden)]
enum TaskRuns {
    Table,
    Id,
    TaskId,
    Status,
    Logs,
    Answer,
    CreatedAt,
}

#[derive(DeriveIden)]
enum Tasks {
    Table,
    Id,
    Status,
    Logs,
    Answer,
}