//go:build ignore
// +build ignore

// This generates countries.go by running "go generate"
package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"text/template"
)

func gen_migrations(name string) {
	if name == "" {
		return
	}

	dialect := strings.ToLower(name)

	type Migration struct {
		ID      string
		Dialect string
		Query   string
	}

	var migrations []Migration

	// Folder in which migration files are stored.
	folder := "./" + dialect

	// Returns directory entries sorted by filename.
	files, _ := os.ReadDir(folder)

	fmt.Printf("generating %s...", dialect)

	// Read migrations from files.
	for _, file := range files {
		filePath := filepath.Join(folder, file.Name())

		if file.IsDir() {
			continue
		} else if id := strings.SplitN(filepath.Base(file.Name()), ".", 2)[0]; id == "" {
			fmt.Printf("e")
			// Ignore.
		} else if query, err := os.ReadFile(filePath); err == nil && len(query) > 0 {
			fmt.Printf(".")
			migrations = append(migrations, Migration{ID: id, Dialect: dialect, Query: string(query)})
		} else {
			fmt.Printf("f")
			fmt.Println(err.Error())
		}
	}

	fmt.Printf(" found %d migrations\n", len(migrations))

	// Create source file from migrations.
	f, err := os.Create(fmt.Sprintf("dialect_%s.go", dialect))

	if err != nil {
		panic(err)
	}

	defer f.Close()

	// Render source template.
	migrationsTemplate.Execute(f, struct {
		Name       string
		Migrations []Migration
	}{
		Name:       name,
		Migrations: migrations,
	})
}

func main() {
	gen_migrations("MySQL")
	gen_migrations("SQLite")
}

var migrationsTemplate = template.Must(template.New("").Parse(`// Code generated by go generate; DO NOT EDIT.
package migrate

var Dialect{{ print .Name }} = Migrations{
{{- range .Migrations }}
	{
		ID:      {{ printf "%q" .ID }},
		Dialect: {{ printf "%q" .Dialect }},
		Query:   {{ printf "%q" .Query }},
	},	
{{- end }}
}`))