package build

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"sort"
)

const registryFileName = "registry.gen.go"

type registryRef struct {
	Package string
	Ident   string
}

type registryData struct {
	Package          string
	Module           string
	Imports          []string
	Models           []registryRef
	Migrations       []registryRef
	Commands         []registryRef
	Jobs             []registryRef
	AdminControllers []registryRef
}

func emptyRegistry(pkg, module string) registryData {
	data := registryData{Package: pkg, Module: module}
	data.prepare()
	return data
}

func (d *registryData) prepare() {
	d.Imports = uniqueLeafImports(d.Module, d.Models, d.Migrations, d.Commands, d.Jobs, d.AdminControllers)
}

func uniqueLeafImports(module string, groups ...[]registryRef) []string {
	if module == "" {
		return nil
	}
	seen := make(map[string]struct{})
	var imports []string
	for _, group := range groups {
		for _, ref := range group {
			if ref.Package == "" {
				continue
			}
			path := module + "/" + ref.Package
			if _, ok := seen[path]; ok {
				continue
			}
			seen[path] = struct{}{}
			imports = append(imports, path)
		}
	}
	sort.Strings(imports)
	return imports
}

func writeRegistry(pluginDir string, data registryData) error {
	data.prepare()
	src, err := renderStub("registry.go", data)
	if err != nil {
		return err
	}
	path := filepath.Join(pluginDir, registryFileName)
	existing, err := os.ReadFile(path)
	if err == nil && bytes.Equal(existing, src) {
		return nil
	}
	if err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("build: read %s: %w", path, err)
	}
	tmp, err := os.CreateTemp(pluginDir, registryFileName+".*")
	if err != nil {
		return fmt.Errorf("build: create %s temp: %w", registryFileName, err)
	}
	tmpName := tmp.Name()
	if _, err := tmp.Write(src); err != nil {
		tmp.Close()
		os.Remove(tmpName)
		return fmt.Errorf("build: write %s temp: %w", registryFileName, err)
	}
	if err := tmp.Close(); err != nil {
		os.Remove(tmpName)
		return fmt.Errorf("build: close %s temp: %w", registryFileName, err)
	}
	if err := os.Rename(tmpName, path); err != nil {
		os.Remove(tmpName)
		return fmt.Errorf("build: rename %s: %w", registryFileName, err)
	}
	return nil
}