package config

import (
	"fmt"
	"github.com/pkg/errors"
	"io/ioutil"

	"github.com/santhosh-tekuri/jsonschema"
	"gopkg.in/yaml.v2"
)

// Config is for top-level struct for config
type Config struct {
	Telegram TelegramConfig `yaml:":telegram"`
	XMPP     XMPPConfig     `yaml:":xmpp"`
}

// XMPPConfig is for :xmpp: subtree
type XMPPConfig struct {
	Loglevel string `yaml:":loglevel"`
	Jid      string `yaml:":jid"`
	Host     string `yaml:":host"`
	Port     string `yaml:":port"`
	Password string `yaml:":password"`
	Db       string `yaml:":db"`
}

// TelegramConfig is for :telegram: subtree
type TelegramConfig struct {
	Loglevel  string                `yaml:":loglevel"`
	Content   TelegramContentConfig `yaml:":content"`
	Verbosity uint8                 `yaml:":tdlib_verbosity"`
	Tdlib     TelegramTdlibConfig   `yaml:":tdlib"`
}

// TelegramContentConfig is for :content: subtree
type TelegramContentConfig struct {
	Path   string `yaml:":path"`
	Link   string `yaml:":link"`
	Upload string `yaml:":upload"`
	User   string `yaml:":user"`
}

// TelegramTdlibConfig is for :tdlib: subtree
type TelegramTdlibConfig struct {
	Datadir string                    `yaml:":datadir"`
	Client  TelegramTdlibClientConfig `yaml:":client"`
}

// TelegramTdlibClientConfig is for :client: subtree
type TelegramTdlibClientConfig struct {
	APIID               string `yaml:":api_id"`
	APIHash             string `yaml:":api_hash"`
	DeviceModel         string `yaml:":device_model"`
	ApplicationVersion  string `yaml:":application_version"`
	UseChatInfoDatabase bool   `yaml:":use_chat_info_database"`
	UseSecretChats      bool   `yaml:":use_secret_chats"`
	CatchTimeout        int64  `yaml:":catch_timeout"`
}

// ReadConfig reads the specified config file, validates it and returns a struct
func ReadConfig(path string, schemaPath string) (Config, error) {
	var config Config

	file, err := ioutil.ReadFile(path)
	if err != nil {
		return config, errors.Wrap(err, "Can't open config file")
	}

	err = yaml.Unmarshal(file, &config)
	if err != nil {
		return config, errors.Wrap(err, "Error parsing config")
	}

	err = validateConfig(file, schemaPath)
	if err != nil {
		return config, errors.Wrap(err, "Validation error")
	}

	return config, nil
}

func validateConfig(file []byte, schemaPath string) error {
	schema, err := jsonschema.Compile(schemaPath)
	if err != nil {
		return errors.Wrap(err, "Corrupted JSON schema")
	}

	var configGeneric interface{}

	err = yaml.Unmarshal(file, &configGeneric)
	if err != nil {
		return errors.Wrap(err, "Error re-parsing config")
	}

	configGeneric, err = convertToStringKeysRecursive(configGeneric, "")
	if err != nil {
		return errors.Wrap(err, "Config conversion error")
	}

	err = schema.ValidateInterface(configGeneric)
	if err != nil {
		return errors.Wrap(err, "Config validation error")
	}

	return nil
}

// copied and adapted from https://github.com/docker/docker-ce/blob/de14285fad39e215ea9763b8b404a37686811b3f/components/cli/cli/compose/loader/loader.go#L330
func convertToStringKeysRecursive(value interface{}, keyPrefix string) (interface{}, error) {
	if mapping, ok := value.(map[interface{}]interface{}); ok {
		dict := make(map[string]interface{})
		for key, entry := range mapping {
			str, ok := key.(string)
			if !ok {
				return nil, formatInvalidKeyError(keyPrefix, key)
			}
			var newKeyPrefix string
			if keyPrefix == "" {
				newKeyPrefix = str
			} else {
				newKeyPrefix = fmt.Sprintf("%s.%s", keyPrefix, str)
			}
			convertedEntry, err := convertToStringKeysRecursive(entry, newKeyPrefix)
			if err != nil {
				return nil, err
			}
			dict[str] = convertedEntry
		}
		return dict, nil
	}
	if list, ok := value.([]interface{}); ok {
		var convertedList []interface{}
		for index, entry := range list {
			newKeyPrefix := fmt.Sprintf("%s[%d]", keyPrefix, index)
			convertedEntry, err := convertToStringKeysRecursive(entry, newKeyPrefix)
			if err != nil {
				return nil, err
			}
			convertedList = append(convertedList, convertedEntry)
		}
		return convertedList, nil
	}

	return value, nil
}

func formatInvalidKeyError(keyPrefix string, key interface{}) error {
	var location string
	if keyPrefix == "" {
		location = "at top level"
	} else {
		location = fmt.Sprintf("in %s", keyPrefix)
	}
	return errors.Errorf("Non-string key %s: %#v", location, key)
}