package config

import (
	"fmt"
	"io"
	"strings"
)

// PrintEnvVars writes all environment variables and their documentation to the provided writer
func PrintEnvVars(w io.Writer) error {
	envVars := GetAllEnvVars()
	
	// Find the longest name for alignment
	maxNameLen := 0
	for _, ev := range envVars {
		if len(ev.Name) > maxNameLen {
			maxNameLen = len(ev.Name)
		}
	}
	
	// Print header
	fmt.Fprintln(w, "Environment Variables")
	fmt.Fprintln(w, strings.Repeat("=", 80))
	fmt.Fprintln(w)
	
	// 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(w, "%s\n", groupTitles[prefix])
		fmt.Fprintln(w, strings.Repeat("-", len(groupTitles[prefix])))
		
		for _, ev := range vars {
			padding := strings.Repeat(" ", maxNameLen-len(ev.Name))
			if ev.Required {
				fmt.Fprintf(w, "  %s%s : %s (required)\n", ev.Name, padding, ev.Description)
			} else if ev.HasDefault {
				fmt.Fprintf(w, "  %s%s : %s (default: %s)\n", ev.Name, padding, ev.Description, ev.Default)
			} else {
				fmt.Fprintf(w, "  %s%s : %s\n", ev.Name, padding, ev.Description)
			}
		}
		fmt.Fprintln(w)
	}
	
	return nil
}