package config

import (
	"fmt"
	"io"
	"net/url"
	"os"
	"path/filepath"
	"reflect"
	"slices"
	"strconv"
	"strings"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	"github.com/thomiceli/opengist/internal/utils"
	"gopkg.in/yaml.v3"
)

var OpengistVersion = ""

var C *config

var SecretKey []byte

// Not using nested structs because the library
// doesn't support dot notation in this case sadly
type config struct {
	SecretKey string `yaml:"secret-key" env:"OG_SECRET_KEY"`

	LogLevel     string `yaml:"log-level" env:"OG_LOG_LEVEL"`
	LogOutput    string `yaml:"log-output" env:"OG_LOG_OUTPUT"`
	ExternalUrl  string `yaml:"external-url" env:"OG_EXTERNAL_URL"`
	OpengistHome string `yaml:"opengist-home" env:"OG_OPENGIST_HOME"`

	DBUri      string `yaml:"db-uri" env:"OG_DB_URI"`
	DBFilename string `yaml:"db-filename" env:"OG_DB_FILENAME"` // deprecated

	IndexEnabled bool   `yaml:"index.enabled" env:"OG_INDEX_ENABLED"`
	IndexDirname string `yaml:"index.dirname" env:"OG_INDEX_DIRNAME"`

	GitDefaultBranch string `yaml:"git.default-branch" env:"OG_GIT_DEFAULT_BRANCH"`

	SqliteJournalMode string `yaml:"sqlite.journal-mode" env:"OG_SQLITE_JOURNAL_MODE"`

	HttpHost string `yaml:"http.host" env:"OG_HTTP_HOST"`
	HttpPort string `yaml:"http.port" env:"OG_HTTP_PORT"`
	HttpGit  bool   `yaml:"http.git-enabled" env:"OG_HTTP_GIT_ENABLED"`

	SshGit            bool   `yaml:"ssh.git-enabled" env:"OG_SSH_GIT_ENABLED"`
	SshHost           string `yaml:"ssh.host" env:"OG_SSH_HOST"`
	SshPort           string `yaml:"ssh.port" env:"OG_SSH_PORT"`
	SshExternalDomain string `yaml:"ssh.external-domain" env:"OG_SSH_EXTERNAL_DOMAIN"`
	SshKeygen         string `yaml:"ssh.keygen-executable" env:"OG_SSH_KEYGEN_EXECUTABLE"`

	GithubClientKey string `yaml:"github.client-key" env:"OG_GITHUB_CLIENT_KEY"`
	GithubSecret    string `yaml:"github.secret" env:"OG_GITHUB_SECRET"`

	GitlabClientKey string `yaml:"gitlab.client-key" env:"OG_GITLAB_CLIENT_KEY"`
	GitlabSecret    string `yaml:"gitlab.secret" env:"OG_GITLAB_SECRET"`
	GitlabUrl       string `yaml:"gitlab.url" env:"OG_GITLAB_URL"`
	GitlabName      string `yaml:"gitlab.name" env:"OG_GITLAB_NAME"`

	GiteaClientKey string `yaml:"gitea.client-key" env:"OG_GITEA_CLIENT_KEY"`
	GiteaSecret    string `yaml:"gitea.secret" env:"OG_GITEA_SECRET"`
	GiteaUrl       string `yaml:"gitea.url" env:"OG_GITEA_URL"`
	GiteaName      string `yaml:"gitea.name" env:"OG_GITEA_NAME"`

	OIDCClientKey    string `yaml:"oidc.client-key" env:"OG_OIDC_CLIENT_KEY"`
	OIDCSecret       string `yaml:"oidc.secret" env:"OG_OIDC_SECRET"`
	OIDCDiscoveryUrl string `yaml:"oidc.discovery-url" env:"OG_OIDC_DISCOVERY_URL"`

	CustomName    string       `yaml:"custom.name" env:"OG_CUSTOM_NAME"`
	CustomLogo    string       `yaml:"custom.logo" env:"OG_CUSTOM_LOGO"`
	CustomFavicon string       `yaml:"custom.favicon" env:"OG_CUSTOM_FAVICON"`
	StaticLinks   []StaticLink `yaml:"custom.static-links" env:"OG_CUSTOM_STATIC_LINK"`
}

type StaticLink struct {
	Name string `yaml:"name" env:"OG_CUSTOM_STATIC_LINK_#_NAME"`
	Path string `yaml:"path" env:"OG_CUSTOM_STATIC_LINK_#_PATH"`
}

func configWithDefaults() (*config, error) {
	c := &config{}

	c.SecretKey = ""

	c.LogLevel = "warn"
	c.LogOutput = "stdout,file"
	c.OpengistHome = ""
	c.DBUri = "opengist.db"
	c.IndexEnabled = true
	c.IndexDirname = "opengist.index"

	c.SqliteJournalMode = "WAL"

	c.HttpHost = "0.0.0.0"
	c.HttpPort = "6157"
	c.HttpGit = true

	c.SshGit = true
	c.SshHost = "0.0.0.0"
	c.SshPort = "2222"
	c.SshKeygen = "ssh-keygen"

	c.GitlabName = "GitLab"

	c.GiteaUrl = "https://gitea.com"
	c.GiteaName = "Gitea"

	return c, nil
}

func InitConfig(configPath string, out io.Writer) error {
	// Default values
	c, err := configWithDefaults()
	if err != nil {
		return err
	}

	if err = loadConfigFromYaml(c, configPath, out); err != nil {
		return err
	}

	if err = loadConfigFromEnv(c, out); err != nil {
		return err
	}

	if c.OpengistHome == "" {
		homeDir, err := os.UserHomeDir()
		if err != nil {
			return fmt.Errorf("opengist home directory is not set and current user home directory could not be determined; please specify the opengist home directory manually via the configuration")
		}

		c.OpengistHome = filepath.Join(homeDir, ".opengist")
	}

	if err = checks(c); err != nil {
		return err
	}

	C = c

	if err = migrateConfig(); err != nil {
		return err
	}

	if err = os.Setenv("OG_OPENGIST_HOME_INTERNAL", GetHomeDir()); err != nil {
		return err
	}
	return nil
}

func InitLog() {
	if err := os.MkdirAll(filepath.Join(GetHomeDir(), "log"), 0755); err != nil {
		panic(err)
	}

	var level zerolog.Level
	level, err := zerolog.ParseLevel(C.LogLevel)
	if err != nil {
		level = zerolog.InfoLevel
	}

	var logWriters []io.Writer
	logOutputTypes := utils.RemoveDuplicates[string](
		strings.Split(strings.ToLower(C.LogOutput), ","),
	)

	consoleWriter := zerolog.NewConsoleWriter(
		func(w *zerolog.ConsoleWriter) {
			w.TimeFormat = time.TimeOnly
			w.FormatCaller = func(i interface{}) string {
				file := i.(string)
				index := strings.Index(file, "internal")
				if index == -1 {
					return file
				}
				return file[index:]
			}
		},
	)

	for _, logOutputType := range logOutputTypes {
		logOutputType = strings.TrimSpace(logOutputType)
		if !slices.Contains([]string{"stdout", "file"}, logOutputType) {
			defer func() { log.Warn().Msg("Invalid log output type: " + logOutputType) }()
			continue
		}

		switch logOutputType {
		case "stdout":
			logWriters = append(logWriters, consoleWriter)
			defer func() { log.Debug().Msg("Logging to stdout") }()
		case "file":
			file, err := os.OpenFile(filepath.Join(GetHomeDir(), "log", "opengist.log"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
			if err != nil {
				panic(err)
			}
			logWriters = append(logWriters, file)
			defer func() { log.Debug().Msg("Logging to file: " + file.Name()) }()
		}
	}
	if len(logWriters) == 0 {
		logWriters = append(logWriters, consoleWriter)
		defer func() { log.Warn().Msg("No valid log outputs, defaulting to stdout") }()
	}

	multi := zerolog.MultiLevelWriter(logWriters...)
	log.Logger = zerolog.New(multi).Level(level).With().Caller().Timestamp().Logger()

	if !slices.Contains([]string{"debug", "info", "warn", "error", "fatal"}, strings.ToLower(C.LogLevel)) {
		log.Warn().Msg("Invalid log level: " + C.LogLevel)
	}
}

func CheckGitVersion(version string) (bool, error) {
	versionParts := strings.Split(version, ".")
	if len(versionParts) < 2 {
		return false, fmt.Errorf("invalid version string")
	}
	major, err := strconv.Atoi(versionParts[0])
	if err != nil {
		return false, fmt.Errorf("invalid major version number")
	}
	minor, err := strconv.Atoi(versionParts[1])
	if err != nil {
		return false, fmt.Errorf("invalid minor version number")
	}

	// Check if version is prior to 2.28
	if major < 2 || (major == 2 && minor < 28) {
		return false, nil
	}
	return true, nil
}

func GetHomeDir() string {
	absolutePath, _ := filepath.Abs(C.OpengistHome)
	return filepath.Clean(absolutePath)
}

func SetupSecretKey() {
	if C.SecretKey == "" {
		path := filepath.Join(GetHomeDir(), "opengist-secret.key")
		SecretKey, _ = utils.GenerateSecretKey(path)
	} else {
		SecretKey = []byte(C.SecretKey)
	}
}

func loadConfigFromYaml(c *config, configPath string, out io.Writer) error {
	if configPath != "" {
		absolutePath, _ := filepath.Abs(configPath)
		absolutePath = filepath.Clean(absolutePath)
		file, err := os.Open(absolutePath)
		if err != nil {
			if !os.IsNotExist(err) {
				return err
			}
			_, _ = fmt.Fprintln(out, "No YAML config file found at "+absolutePath)
		} else {
			_, _ = fmt.Fprintln(out, "Using YAML config file: "+absolutePath)

			// Override default values with values from config.yml
			d := yaml.NewDecoder(file)
			if err = d.Decode(&c); err != nil {
				return err
			}
			defer file.Close()
		}
	} else {
		_, _ = fmt.Fprintln(out, "No YAML config file specified.")
	}

	return nil
}

func loadConfigFromEnv(c *config, out io.Writer) error {
	v := reflect.ValueOf(c).Elem()
	var envVars []string

	for i := 0; i < v.NumField(); i++ {
		tag := v.Type().Field(i).Tag.Get("env")

		if tag == "" {
			continue
		}

		envValue := os.Getenv(strings.ToUpper(tag))
		if envValue == "" && v.Field(i).Kind() != reflect.Slice {
			continue
		}

		switch v.Field(i).Kind() {
		case reflect.String:
			v.Field(i).SetString(envValue)
			envVars = append(envVars, tag)
		case reflect.Bool:
			boolVal, err := strconv.ParseBool(envValue)
			if err != nil {
				return err
			}
			v.Field(i).SetBool(boolVal)
			envVars = append(envVars, tag)
		case reflect.Slice:
			if v.Type().Field(i).Type.Elem().Kind() == reflect.Struct {
				prefix := strings.ToUpper(tag) + "_"
				var sliceValue reflect.Value
				elemType := v.Type().Field(i).Type.Elem()

				for index := 0; ; index++ {
					allFieldsPresent := true
					elemValue := reflect.New(elemType).Elem()

					for j := 0; j < elemValue.NumField() && allFieldsPresent; j++ {
						elemField := elemValue.Type().Field(j)
						envName := fmt.Sprintf("%s%d_%s", prefix, index, strings.ToUpper(elemField.Name))
						envValue, present := os.LookupEnv(envName)

						if !present {
							allFieldsPresent = false
							break
						}

						envVars = append(envVars, envName)
						elemValue.Field(j).SetString(envValue)
					}

					if !allFieldsPresent {
						break
					}

					if sliceValue.Kind() != reflect.Slice {
						sliceValue = reflect.MakeSlice(v.Type().Field(i).Type, 0, index+1)
					}
					sliceValue = reflect.Append(sliceValue, elemValue)
				}

				if sliceValue.IsValid() {
					v.Field(i).Set(sliceValue)
				}
			}
		default:
			return fmt.Errorf("unsupported type: %s", v.Field(i).Kind())
		}

	}

	if len(envVars) > 0 {
		_, _ = fmt.Fprintln(out, "Using environment variables config: "+strings.Join(envVars, ", "))
	} else {
		_, _ = fmt.Fprintln(out, "No environment variables config specified.")
	}

	return nil
}

func checks(c *config) error {
	if _, err := url.Parse(c.ExternalUrl); err != nil {
		return err
	}

	if _, err := url.Parse(c.GiteaUrl); err != nil {
		return err
	}

	if _, err := url.Parse(c.OIDCDiscoveryUrl); err != nil {
		return err
	}

	return nil
}