package config

import (
	"fmt"
	"os"
	"strings"
)

// GenerateDotEnv creates a new .env file with all environment variables and their defaults
func GenerateDotEnv(filename string) error {
	envVars := GetAllEnvVars()

	file, err := os.Create(filename)
	if err != nil {
		return fmt.Errorf("failed to create file: %w", err)
	}
	defer file.Close()

	// Write header
	fmt.Fprintln(file, "# Environment Configuration")
	fmt.Fprintln(file, "# Generated by Project Reshoot")
	fmt.Fprintln(file, "#")
	fmt.Fprintln(file, "# Variables marked as (required) must be set")
	fmt.Fprintln(file, "# Variables with defaults can be left commented out to use the default value")
	fmt.Fprintln(file)

	// Group by prefix
	groups := map[string][]EnvVar{
		"DB_":      {},
		"HWS_":     {},
		"HWSAUTH_": {},
		"TMDB_":    {},
		"LOG_":     {},
	}

	for _, ev := range envVars {
		assigned := false
		for prefix := range groups {
			if strings.HasPrefix(ev.Name, prefix) {
				groups[prefix] = append(groups[prefix], ev)
				assigned = true
				break
			}
		}
		if !assigned {
			// Handle ungrouped vars
			if _, ok := groups["OTHER"]; !ok {
				groups["OTHER"] = []EnvVar{}
			}
			groups["OTHER"] = append(groups["OTHER"], ev)
		}
	}

	// Print each group
	groupOrder := []string{"DB_", "HWS_", "HWSAUTH_", "TMDB_", "LOG_", "OTHER"}
	groupTitles := map[string]string{
		"DB_":      "Database Configuration",
		"HWS_":     "HTTP Web Server Configuration",
		"HWSAUTH_": "Authentication Configuration",
		"TMDB_":    "TMDB API Configuration",
		"LOG_":     "Logging Configuration",
		"OTHER":    "Other Configuration",
	}

	for _, prefix := range groupOrder {
		vars, ok := groups[prefix]
		if !ok || len(vars) == 0 {
			continue
		}

		fmt.Fprintf(file, "# %s\n", groupTitles[prefix])
		fmt.Fprintln(file, strings.Repeat("#", len(groupTitles[prefix])+2))

		for _, ev := range vars {
			// Write description as comment
			if ev.Required {
				fmt.Fprintf(file, "# %s (required)\n", ev.Description)
				// Leave required variables uncommented but empty
				fmt.Fprintf(file, "%s=\n", ev.Name)
			} else if ev.HasDefault {
				fmt.Fprintf(file, "# %s\n", ev.Description)
				// Comment out variables with defaults
				fmt.Fprintf(file, "# %s=%s\n", ev.Name, ev.Default)
			} else {
				fmt.Fprintf(file, "# %s\n", ev.Description)
				// Optional variables without defaults are commented out
				fmt.Fprintf(file, "# %s=\n", ev.Name)
			}
			fmt.Fprintln(file)
		}
		fmt.Fprintln(file)
	}

	return nil
}