// Package config loads and validates SoloPM's environment-variable configuration.
package config

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

// Config holds every environment-driven setting for the SoloPM server.
type Config struct {
	DatabaseURL   string
	HTTPPort      string
	BaseURL       string
	SessionSecret string
	UploadDir     string
	MaxUploadMB   int

	MeiliURL string
	MeiliKey string

	SMTPHost string
	SMTPPort string
	SMTPUser string
	SMTPPass string
	SMTPFrom string

	GitHubClientID     string
	GitHubClientSecret string

	GiteaURL          string
	GiteaClientID     string
	GiteaClientSecret string

	CullAfterDays int
	LogLevel      string
}

// SearchEnabled reports whether Meilisearch is configured.
func (c *Config) SearchEnabled() bool {
	return c.MeiliURL != "" && c.MeiliKey != ""
}

// EmailEnabled reports whether SMTP is configured.
func (c *Config) EmailEnabled() bool {
	return c.SMTPHost != ""
}

// GitHubOAuthEnabled reports whether GitHub OAuth is configured.
func (c *Config) GitHubOAuthEnabled() bool {
	return c.GitHubClientID != "" && c.GitHubClientSecret != ""
}

// GiteaOAuthEnabled reports whether Gitea OAuth is configured.
func (c *Config) GiteaOAuthEnabled() bool {
	return c.GiteaURL != "" && c.GiteaClientID != "" && c.GiteaClientSecret != ""
}

// Load reads configuration from the environment, applying defaults and
// failing fast (returning an error) if a required variable is missing or
// malformed.
func Load() (*Config, error) {
	var missing []string
	required := func(key string) string {
		v := os.Getenv(key)
		if v == "" {
			missing = append(missing, key)
		}
		return v
	}

	c := &Config{
		DatabaseURL:   required("DATABASE_URL"),
		HTTPPort:      getDefault("HTTP_PORT", "8080"),
		BaseURL:       required("BASE_URL"),
		SessionSecret: required("SESSION_SECRET"),
		UploadDir:     getDefault("UPLOAD_DIR", "./uploads"),

		MeiliURL: os.Getenv("MEILI_URL"),
		MeiliKey: os.Getenv("MEILI_KEY"),

		SMTPHost: os.Getenv("SMTP_HOST"),
		SMTPPort: os.Getenv("SMTP_PORT"),
		SMTPUser: os.Getenv("SMTP_USER"),
		SMTPPass: os.Getenv("SMTP_PASS"),
		SMTPFrom: os.Getenv("SMTP_FROM"),

		GitHubClientID:     os.Getenv("GITHUB_CLIENT_ID"),
		GitHubClientSecret: os.Getenv("GITHUB_CLIENT_SECRET"),

		GiteaURL:          os.Getenv("GITEA_URL"),
		GiteaClientID:     os.Getenv("GITEA_CLIENT_ID"),
		GiteaClientSecret: os.Getenv("GITEA_CLIENT_SECRET"),

		LogLevel: getDefault("LOG_LEVEL", "info"),
	}

	if len(missing) > 0 {
		return nil, fmt.Errorf("config: missing required environment variable(s): %s", strings.Join(missing, ", "))
	}

	if len(c.SessionSecret) < 32 {
		return nil, fmt.Errorf("config: SESSION_SECRET must be at least 32 bytes, got %d", len(c.SessionSecret))
	}

	maxUploadMB, err := getIntDefault("MAX_UPLOAD_MB", 25)
	if err != nil {
		return nil, err
	}
	c.MaxUploadMB = maxUploadMB

	cullAfterDays, err := getIntDefault("CULL_AFTER_DAYS", 30)
	if err != nil {
		return nil, err
	}
	c.CullAfterDays = cullAfterDays

	return c, nil
}

func getDefault(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

func getIntDefault(key string, def int) (int, error) {
	v := os.Getenv(key)
	if v == "" {
		return def, nil
	}
	n, err := strconv.Atoi(v)
	if err != nil {
		return 0, fmt.Errorf("config: %s must be an integer, got %q", key, v)
	}
	return n, nil
}