package store

import (
	"context"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"
)

// RunMigrations creates the conversations and messages tables idempotently.
// It is safe to call multiple times; existing tables are left untouched.
//
// Schema:
//
//	conversations(id UUID PK, started_at TIMESTAMPTZ, model TEXT)
//	messages(id UUID PK, conversation_id UUID FK, role TEXT CHECK, content TEXT, created_at TIMESTAMPTZ)
func RunMigrations(ctx context.Context, pool *pgxpool.Pool) error {
	statements := []string{
		`CREATE TABLE IF NOT EXISTS conversations (
			id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
			started_at TIMESTAMPTZ NOT NULL DEFAULT now(),
			model      TEXT NOT NULL DEFAULT ''
		)`,
		`CREATE TABLE IF NOT EXISTS messages (
			id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
			conversation_id UUID NOT NULL REFERENCES conversations(id) ON DELETE CASCADE,
			role            TEXT NOT NULL CHECK (role IN ('user','assistant','system')),
			content         TEXT NOT NULL,
			created_at      TIMESTAMPTZ NOT NULL DEFAULT now()
		)`,
	}

	for i, stmt := range statements {
		if _, err := pool.Exec(ctx, stmt); err != nil {
			return fmt.Errorf("store: migration statement %d: %w", i, err)
		}
	}

	return nil
}