// Command migrate applies or reverts database schema migrations for the
// Pangolin server.
//
// Usage:
//
//	migrate up       – apply all pending migrations
//	migrate down     – revert all applied migrations
//	migrate version  – print the current migration version
//
// Configuration is read from environment variables (PANGOLIN_ prefix).
// Set PANGOLIN_MYSQL_DSN or the individual PANGOLIN_MYSQL_HOST / USER /
// PASSWORD / DBNAME vars before running.
package main

import (
	"fmt"
	"log"
	"os"

	"github.com/wangjia/pangolin/server/internal/config"
	"github.com/wangjia/pangolin/server/internal/store"
)

func main() {
	if len(os.Args) < 2 {
		usage()
		os.Exit(1)
	}
	cmd := os.Args[1]

	cfg, err := config.Load()
	if err != nil {
		log.Fatalf("migrate: config: %v", err)
	}

	db, err := store.Open(cfg)
	if err != nil {
		log.Fatalf("migrate: db: %v", err)
	}
	defer db.Close()

	switch cmd {
	case "up":
		if err := store.MigrateUp(db); err != nil {
			log.Fatalf("migrate up: %v", err)
		}
		log.Println("migrate: up — done")

	case "down":
		if err := store.MigrateDown(db); err != nil {
			log.Fatalf("migrate down: %v", err)
		}
		log.Println("migrate: down — done")

	case "version":
		version, dirty, err := store.MigrateVersion(db)
		if err != nil {
			log.Fatalf("migrate version: %v", err)
		}
		fmt.Printf("migrate: version=%d dirty=%v\n", version, dirty)

	default:
		fmt.Fprintf(os.Stderr, "migrate: unknown command %q\n", cmd)
		usage()
		os.Exit(1)
	}
}

func usage() {
	fmt.Fprintln(os.Stderr, "Usage: migrate <up|down|version>")
	fmt.Fprintln(os.Stderr, "")
	fmt.Fprintln(os.Stderr, "Environment variables:")
	fmt.Fprintln(os.Stderr, "  PANGOLIN_MYSQL_DSN        full DSN (takes precedence)")
	fmt.Fprintln(os.Stderr, "  PANGOLIN_MYSQL_HOST       MySQL host (required if no DSN)")
	fmt.Fprintln(os.Stderr, "  PANGOLIN_MYSQL_PORT       MySQL port (default 3306)")
	fmt.Fprintln(os.Stderr, "  PANGOLIN_MYSQL_USER       MySQL user (required if no DSN)")
	fmt.Fprintln(os.Stderr, "  PANGOLIN_MYSQL_PASSWORD   MySQL password")
	fmt.Fprintln(os.Stderr, "  PANGOLIN_MYSQL_DBNAME     MySQL database (required if no DSN)")
}