package config

import (
	"encoding/json"
	"errors"
	"io/ioutil"
	"os"
	"reflect"
	"strconv"
	"strings"

	"github.com/flynn/json5"
	"github.com/zyedidia/glob"
	"github.com/zyedidia/micro/internal/util"
	"golang.org/x/text/encoding/htmlindex"
)

type optionValidator func(string, interface{}) error

var (
	ErrInvalidOption = errors.New("Invalid option")
	ErrInvalidValue  = errors.New("Invalid value")

	// The options that the user can set
	GlobalSettings map[string]interface{}

	// This is the raw parsed json
	parsedSettings map[string]interface{}
)

// Options with validators
var optionValidators = map[string]optionValidator{
	"tabsize":      validatePositiveValue,
	"scrollmargin": validateNonNegativeValue,
	"scrollspeed":  validateNonNegativeValue,
	"colorscheme":  validateColorscheme,
	"colorcolumn":  validateNonNegativeValue,
	"fileformat":   validateLineEnding,
	"encoding":     validateEncoding,
}

func ReadSettings() error {
	filename := ConfigDir + "/settings.json"
	if _, e := os.Stat(filename); e == nil {
		input, err := ioutil.ReadFile(filename)
		if err != nil {
			return errors.New("Error reading settings.json file: " + err.Error())
		}
		if !strings.HasPrefix(string(input), "null") {
			// Unmarshal the input into the parsed map
			err = json5.Unmarshal(input, &parsedSettings)
			if err != nil {
				return errors.New("Error reading settings.json: " + err.Error())
			}
		}
	}
	return nil
}

// InitGlobalSettings initializes the options map and sets all options to their default values
// Must be called after ReadSettings
func InitGlobalSettings() {
	GlobalSettings = DefaultGlobalSettings()

	for k, v := range parsedSettings {
		if !strings.HasPrefix(reflect.TypeOf(v).String(), "map") {
			GlobalSettings[k] = v
		}
	}
}

// InitLocalSettings scans the json in settings.json and sets the options locally based
// on whether the filetype or path matches ft or glob local settings
// Must be called after ReadSettings
func InitLocalSettings(settings map[string]interface{}, path string) error {
	var parseError error
	for k, v := range parsedSettings {
		if strings.HasPrefix(reflect.TypeOf(v).String(), "map") {
			if strings.HasPrefix(k, "ft:") {
				if settings["filetype"].(string) == k[3:] {
					for k1, v1 := range v.(map[string]interface{}) {
						settings[k1] = v1
					}
				}
			} else {
				g, err := glob.Compile(k)
				if err != nil {
					parseError = errors.New("Error with glob setting " + k + ": " + err.Error())
					continue
				}

				if g.MatchString(path) {
					for k1, v1 := range v.(map[string]interface{}) {
						settings[k1] = v1
					}
				}
			}
		}
	}
	return parseError
}

// WriteSettings writes the settings to the specified filename as JSON
func WriteSettings(filename string) error {
	var err error
	if _, e := os.Stat(ConfigDir); e == nil {
		for k, v := range GlobalSettings {
			parsedSettings[k] = v
		}

		txt, _ := json.MarshalIndent(parsedSettings, "", "    ")
		err = ioutil.WriteFile(filename, append(txt, '\n'), 0644)
	}
	return err
}

// AddOption creates a new option. This is meant to be called by plugins to add options.
func AddOption(name string, value interface{}) error {
	GlobalSettings[name] = value
	err := WriteSettings(ConfigDir + "/settings.json")
	if err != nil {
		return errors.New("Error writing settings.json file: " + err.Error())
	}
	return nil
}

// GetGlobalOption returns the global value of the given option
func GetGlobalOption(name string) interface{} {
	return GlobalSettings[name]
}

func DefaultCommonSettings() map[string]interface{} {
	return map[string]interface{}{
		"autoindent":     true,
		"autosave":       false,
		"basename":       false,
		"colorcolumn":    float64(0),
		"cursorline":     true,
		"encoding":       "utf-8",
		"eofnewline":     false,
		"fastdirty":      true,
		"fileformat":     "unix",
		"ignorecase":     false,
		"indentchar":     " ",
		"keepautoindent": false,
		"matchbrace":     false,
		"matchbraceleft": false,
		"rmtrailingws":   false,
		"ruler":          true,
		"savecursor":     false,
		"saveundo":       false,
		"scrollbar":      false,
		"scrollmargin":   float64(3),
		"scrollspeed":    float64(2),
		"smartpaste":     true,
		"softwrap":       false,
		"splitbottom":    true,
		"splitright":     true,
		"statusformatl":  "$(filename) $(modified)($(line),$(col)) $(opt:filetype) $(opt:fileformat) $(opt:encoding)",
		"statusformatr":  "$(bind:ToggleKeyMenu): show bindings, $(bind:ToggleHelp): toggle help",
		"statusline":     true,
		"syntax":         true,
		"tabmovement":    false,
		"tabsize":        float64(4),
		"tabstospaces":   false,
		"useprimary":     true,
	}
}

func GetInfoBarOffset() int {
	offset := 0
	if GetGlobalOption("infobar").(bool) {
		offset++
	}
	if GetGlobalOption("keymenu").(bool) {
		offset += 2
	}
	return offset
}

// DefaultGlobalSettings returns the default global settings for micro
// Note that colorscheme is a global only option
func DefaultGlobalSettings() map[string]interface{} {
	common := DefaultCommonSettings()
	common["colorscheme"] = "default"
	common["infobar"] = true
	common["keymenu"] = false
	common["mouse"] = true
	common["pluginchannels"] = []string{"https://raw.githubusercontent.com/micro-editor/plugin-channel/master/channel.json"}
	common["pluginrepos"] = []string{}
	common["savehistory"] = true
	common["sucmd"] = "sudo"
	common["termtitle"] = false
	return common
}

// LocalSettings is a list of the local only settings
var LocalSettings = []string{"filetype", "readonly"}

// DefaultLocalSettings returns the default local settings
// Note that filetype is a local only option
func DefaultLocalSettings() map[string]interface{} {
	common := DefaultCommonSettings()
	common["filetype"] = "unknown"
	common["readonly"] = false
	return common
}

func DefaultAllSettings() map[string]interface{} {
	global := DefaultGlobalSettings()
	local := DefaultLocalSettings()
	for k, v := range global {
		local[k] = v
	}
	return local
}

func GetNativeValue(option string, realValue interface{}, value string) (interface{}, error) {
	var native interface{}
	kind := reflect.TypeOf(realValue).Kind()
	if kind == reflect.Bool {
		b, err := util.ParseBool(value)
		if err != nil {
			return nil, ErrInvalidValue
		}
		native = b
	} else if kind == reflect.String {
		native = value
	} else if kind == reflect.Float64 {
		i, err := strconv.Atoi(value)
		if err != nil {
			return nil, ErrInvalidValue
		}
		native = float64(i)
	} else {
		return nil, ErrInvalidValue
	}

	if err := OptionIsValid(option, native); err != nil {
		return nil, err
	}
	return native, nil
}

// OptionIsValid checks if a value is valid for a certain option
func OptionIsValid(option string, value interface{}) error {
	if validator, ok := optionValidators[option]; ok {
		return validator(option, value)
	}

	return nil
}

// Option validators

func validatePositiveValue(option string, value interface{}) error {
	tabsize, ok := value.(float64)

	if !ok {
		return errors.New("Expected numeric type for " + option)
	}

	if tabsize < 1 {
		return errors.New(option + " must be greater than 0")
	}

	return nil
}

func validateNonNegativeValue(option string, value interface{}) error {
	nativeValue, ok := value.(float64)

	if !ok {
		return errors.New("Expected numeric type for " + option)
	}

	if nativeValue < 0 {
		return errors.New(option + " must be non-negative")
	}

	return nil
}

func validateColorscheme(option string, value interface{}) error {
	colorscheme, ok := value.(string)

	if !ok {
		return errors.New("Expected string type for colorscheme")
	}

	if !ColorschemeExists(colorscheme) {
		return errors.New(colorscheme + " is not a valid colorscheme")
	}

	return nil
}

func validateLineEnding(option string, value interface{}) error {
	endingType, ok := value.(string)

	if !ok {
		return errors.New("Expected string type for file format")
	}

	if endingType != "unix" && endingType != "dos" {
		return errors.New("File format must be either 'unix' or 'dos'")
	}

	return nil
}

func validateEncoding(option string, value interface{}) error {
	_, err := htmlindex.Get(value.(string))
	return err
}