// Package main provides the generate command for generating Home Assistant entity constants
package main

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

	"gopkg.in/yaml.v3"
	ga "saml.dev/gome-assistant"
)

type Config struct {
	URL              string `yaml:"url"`
	HAAuthToken      string `yaml:"ha_auth_token"`
	HomeZoneEntityId string `yaml:"home_zone_entity_id"`
}

type Domain struct {
	Name     string
	Entities []Entity
}

type Entity struct {
	FieldName string
	EntityID  string
}

func toFieldName(entityID string) string {
	parts := strings.Split(entityID, ".")
	if len(parts) != 2 {
		return ""
	}
	return toCamelCase(parts[1])
}

func toCamelCase(s string) string {
	if s == "" {
		return ""
	}

	parts := strings.Split(s, "_")
	var result strings.Builder

	// If first character is numeric
	firstChar := parts[0][0]
	if firstChar >= '0' && firstChar <= '9' {
		result.WriteString("_")
	}

	for _, part := range parts {
		if part == "" {
			continue
		}
		result.WriteString(strings.ToUpper(string(part[0])))
		if len(part) > 1 {
			result.WriteString(part[1:])
		}
	}

	return result.String()
}

// generate creates the entities.go file with constants for all Home Assistant entities
func generate(config Config) error {
	app, err := ga.NewApp(ga.NewAppRequest{
		URL:              config.URL,
		HAAuthToken:      config.HAAuthToken,
		HomeZoneEntityId: config.HomeZoneEntityId,
	})
	if err != nil {
		return fmt.Errorf("failed to create app: %w", err)
	}
	defer app.Cleanup()

	entities, err := app.GetState().ListEntities()
	if err != nil {
		return fmt.Errorf("failed to list entities: %w", err)
	}

	// Group entities by domain
	domainMap := make(map[string]*Domain)
	for _, entity := range entities {
		if entity.State == "unavailable" {
			continue
		}

		parts := strings.Split(entity.EntityID, ".")
		if len(parts) != 2 {
			continue
		}

		domain := parts[0]
		if _, exists := domainMap[domain]; !exists {
			domainMap[domain] = &Domain{
				Name: toCamelCase(domain),
			}
		}

		domainMap[domain].Entities = append(domainMap[domain].Entities, Entity{
			FieldName: toFieldName(entity.EntityID),
			EntityID:  entity.EntityID,
		})
	}

	// Map to slice for template
	domains := make([]Domain, 0)
	for _, domain := range domainMap {
		domains = append(domains, *domain)
	}

	// Create entities directory if it doesn't exist
	err = os.MkdirAll("entities", 0755)
	if err != nil {
		return fmt.Errorf("failed to create entities directory: %w", err)
	}

	// Create the file
	tmpl := template.Must(template.New("entities").Parse(`// Code generated by go generate; DO NOT EDIT.
package entities

{{ range .Domains }}
type {{ .Name }}Domain struct {
	{{- range .Entities }}
	{{ .FieldName }} string
	{{- end }}
}

var {{ .Name }} = {{ .Name }}Domain{
	{{- range .Entities }}
	{{ .FieldName }}: "{{ .EntityID }}",
	{{- end }}
}
{{ end }}
`))

	f, err := os.Create(filepath.Join("entities", "entities.go"))
	if err != nil {
		return fmt.Errorf("failed to create entities.go: %w", err)
	}
	defer f.Close()

	err = tmpl.Execute(f, struct{ Domains []Domain }{domains})
	if err != nil {
		return fmt.Errorf("failed to execute template: %w", err)
	}

	return nil
}

func main() {
	println("Generating entities.go...")
	configFile := flag.String("config", "gen.yaml", "Path to config file")
	flag.Parse()

	absConfigPath, err := filepath.Abs(*configFile)
	if err != nil {
		fmt.Printf("Error resolving config path: %v\n", err)
		os.Exit(1)
	}

	configBytes, err := os.ReadFile(absConfigPath)
	if err != nil {
		fmt.Printf("Error reading config file: %v\n", err)
		os.Exit(1)
	}

	var config Config
	if err := yaml.Unmarshal(configBytes, &config); err != nil {
		fmt.Printf("Error parsing config file: %v\n", err)
		os.Exit(1)
	}

	if config.HAAuthToken == "" {
		config.HAAuthToken = os.Getenv("HA_AUTH_TOKEN")
	}

	if config.URL == "" || config.HAAuthToken == "" || config.HomeZoneEntityId == "" {
		fmt.Println("Error: url, ha_auth_token and home_zone_entity_id are required in config")
		os.Exit(1)
	}

	if err := generate(config); err != nil {
		fmt.Printf("Error generating entities: %v\n", err)
		os.Exit(1)
	}

	fmt.Println("Generated entities/entities.go")
}