package app

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/example/glpi-env-controller/internal/dockerctl"
)

type Config struct {
	ListenAddr        string          `json:"listen_addr"`
	Username          string          `json:"username"`
	PasswordEnv       string          `json:"password_env"`
	PasswordFile      string          `json:"password_file"`
	AutoImportMissing bool            `json:"auto_import_missing"`
	MaxBackups        int             `json:"max_backups"`
	DockerTimeout     string          `json:"docker_timeout"`
	Projects          []ProjectConfig `json:"projects"`
}

type ProjectConfig struct {
	ID          string             `json:"id"`
	Title       string             `json:"title"`
	EnvFile     string             `json:"env_file"`
	ExampleFile string             `json:"example_file"`
	BackupDir   string             `json:"backup_dir"`
	Targets     []dockerctl.Target `json:"targets"`
}

func LoadConfig(path string) (Config, string, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return Config{}, "", err
	}
	var cfg Config
	if err := json.Unmarshal(data, &cfg); err != nil {
		return Config{}, "", fmt.Errorf("decode config: %w", err)
	}
	if cfg.ListenAddr == "" {
		cfg.ListenAddr = ":8090"
	}
	if cfg.Username == "" {
		cfg.Username = "admin"
	}
	if cfg.PasswordEnv == "" && cfg.PasswordFile == "" {
		cfg.PasswordEnv = "ENV_CONTROLLER_PASSWORD"
	}
	if cfg.MaxBackups <= 0 {
		cfg.MaxBackups = 100
	}
	if cfg.DockerTimeout == "" {
		cfg.DockerTimeout = "3m"
	}
	if _, err := time.ParseDuration(cfg.DockerTimeout); err != nil {
		return Config{}, "", fmt.Errorf("docker_timeout: %w", err)
	}
	password := ""
	if cfg.PasswordFile != "" {
		data, err := os.ReadFile(cfg.PasswordFile)
		if err != nil {
			return Config{}, "", fmt.Errorf("read password_file: %w", err)
		}
		password = strings.TrimSpace(string(data))
	} else {
		password = os.Getenv(cfg.PasswordEnv)
	}
	if password == "" {
		return Config{}, "", fmt.Errorf("controller password is empty")
	}
	if len(cfg.Projects) == 0 {
		return Config{}, "", fmt.Errorf("at least one project is required")
	}
	seen := map[string]struct{}{}
	for i := range cfg.Projects {
		p := &cfg.Projects[i]
		if p.ID == "" || !safeID(p.ID) {
			return Config{}, "", fmt.Errorf("project %d has invalid id", i)
		}
		if _, ok := seen[p.ID]; ok {
			return Config{}, "", fmt.Errorf("duplicate project id %q", p.ID)
		}
		seen[p.ID] = struct{}{}
		if p.Title == "" {
			p.Title = p.ID
		}
		for label, value := range map[string]string{"env_file": p.EnvFile, "example_file": p.ExampleFile, "backup_dir": p.BackupDir} {
			if value == "" || !filepath.IsAbs(value) {
				return Config{}, "", fmt.Errorf("project %q %s must be an absolute path", p.ID, label)
			}
		}
		if filepath.Clean(p.EnvFile) == filepath.Clean(p.ExampleFile) {
			return Config{}, "", fmt.Errorf("project %q env_file and example_file must differ", p.ID)
		}
		if err := dockerctl.ValidateTargets(p.Targets); err != nil {
			return Config{}, "", fmt.Errorf("project %q targets: %w", p.ID, err)
		}
	}
	return cfg, password, nil
}

func safeID(value string) bool {
	if value == "" {
		return false
	}
	for _, r := range value {
		if !((r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '-' || r == '_') {
			return false
		}
	}
	return !strings.HasPrefix(value, "-")
}