// Readline is a pure go implementation for GNU-Readline kind library.
//
// example:
// 	rl, err := readline.New(readline.StaticPrompt("> "))
// 	if err != nil {
// 		panic(err)
// 	}
// 	defer rl.Close()
//
// 	for {
// 		line, err := rl.Readline()
// 		if err != nil { // io.EOF
// 			break
// 		}
// 		println(line)
// 	}
//
package readline

import (
	"fmt"
	"io"
)

type Instance struct {
	Config    *Config
	Terminal  *Terminal
	Operation *Operation
}

type Config struct {
	// prompt supports ANSI escape sequence, so we can color some characters even in windows
	Prompt fmt.Stringer

	// readline will persist historys to file where HistoryFile specified
	HistoryFile string
	// specify the max length of historys, it's 500 by default, set it to -1 to disable history
	HistoryLimit           int
	DisableAutoSaveHistory bool
	// enable case-insensitive history searching
	HistorySearchFold bool

	// AutoCompleter will called once user press TAB
	AutoComplete AutoCompleter

	// Any key press will pass to Listener
	// NOTE: Listener will be triggered by (nil, 0, 0) immediately
	Listener Listener

	Painter Painter

	// If VimMode is true, readline will in vim.insert mode by default
	VimMode bool

	InterruptPrompt string
	EOFPrompt       string

	FuncGetWidth func() int

	Stdin       io.ReadCloser
	StdinWriter io.Writer
	Stdout      io.Writer
	Stderr      io.Writer

	EnableMask bool
	MaskRune   rune

	// erase the editing line after user submited it
	// it use in IM usually.
	UniqueEditLine bool

	// filter input runes (may be used to disable CtrlZ or for translating some keys to different actions)
	// -> output = new (translated) rune and true/false if continue with processing this one
	FuncFilterInputRune func(rune) (rune, bool)

	// force use interactive even stdout is not a tty
	FuncIsTerminal      func() bool
	FuncMakeRaw         func() error
	FuncExitRaw         func() error
	FuncOnWidthChanged  func(func())
	ForceUseInteractive bool

	// private fields
	inited    bool
	opHistory *opHistory
	opSearch  *opSearch
}

func (c *Config) useInteractive() bool {
	if c.ForceUseInteractive {
		return true
	}
	return c.FuncIsTerminal()
}

func (c *Config) Init() error {
	if c.inited {
		return nil
	}
	c.inited = true
	if c.Stdin == nil {
		c.Stdin = NewCancelableStdin(Stdin)
	}

	c.Stdin, c.StdinWriter = NewFillableStdin(c.Stdin)

	if c.Stdout == nil {
		c.Stdout = Stdout
	}
	if c.Stderr == nil {
		c.Stderr = Stderr
	}
	if c.HistoryLimit == 0 {
		c.HistoryLimit = 500
	}

	if c.InterruptPrompt == "" {
		c.InterruptPrompt = "^C"
	} else if c.InterruptPrompt == "\n" {
		c.InterruptPrompt = ""
	}
	if c.EOFPrompt == "" {
		c.EOFPrompt = "^D"
	} else if c.EOFPrompt == "\n" {
		c.EOFPrompt = ""
	}

	if c.AutoComplete == nil {
		c.AutoComplete = &TabCompleter{}
	}
	if c.FuncGetWidth == nil {
		c.FuncGetWidth = GetScreenWidth
	}
	if c.FuncIsTerminal == nil {
		c.FuncIsTerminal = DefaultIsTerminal
	}
	rm := new(RawMode)
	if c.FuncMakeRaw == nil {
		c.FuncMakeRaw = rm.Enter
	}
	if c.FuncExitRaw == nil {
		c.FuncExitRaw = rm.Exit
	}
	if c.FuncOnWidthChanged == nil {
		c.FuncOnWidthChanged = DefaultOnWidthChanged
	}

	return nil
}

func (c Config) Clone() *Config {
	c.opHistory = nil
	c.opSearch = nil
	return &c
}

func (c *Config) SetListener(f func(line []rune, pos int, key rune) (newLine []rune, newPos int, ok bool)) {
	c.Listener = FuncListener(f)
}

func (c *Config) SetPainter(p Painter) {
	c.Painter = p
}

func NewEx(cfg *Config) (*Instance, error) {
	t, err := NewTerminal(cfg)
	if err != nil {
		return nil, err
	}
	rl := t.Readline()
	if cfg.Painter == nil {
		cfg.Painter = &defaultPainter{}
	}
	return &Instance{
		Config:    cfg,
		Terminal:  t,
		Operation: rl,
	}, nil
}

type Prompter interface {
	String() string
}

func New(prompt fmt.Stringer) (*Instance, error) {
	return NewEx(&Config{Prompt: prompt})
}

func (i *Instance) ResetHistory() {
	i.Operation.ResetHistory()
}

func (i *Instance) SetPrompt(s fmt.Stringer) {
	i.Operation.SetPrompt(s)
}

func (i *Instance) SetMaskRune(r rune) {
	i.Operation.SetMaskRune(r)
}

// change history persistence in runtime
func (i *Instance) SetHistoryPath(p string) {
	i.Operation.SetHistoryPath(p)
}

// readline will refresh automatic when write through Stdout()
func (i *Instance) Stdout() io.Writer {
	return i.Operation.Stdout()
}

// readline will refresh automatic when write through Stdout()
func (i *Instance) Stderr() io.Writer {
	return i.Operation.Stderr()
}

// switch VimMode in runtime
func (i *Instance) SetVimMode(on bool) {
	i.Operation.SetVimMode(on)
}

func (i *Instance) IsVimMode() bool {
	return i.Operation.IsEnableVimMode()
}

func (i *Instance) GenPasswordConfig() *Config {
	return i.Operation.GenPasswordConfig()
}

// we can generate a config by `i.GenPasswordConfig()`
func (i *Instance) ReadPasswordWithConfig(cfg *Config) ([]byte, error) {
	return i.Operation.PasswordWithConfig(cfg)
}

func (i *Instance) ReadPasswordEx(prompt fmt.Stringer, l Listener) ([]byte, error) {
	return i.Operation.PasswordEx(prompt, l)
}

func (i *Instance) ReadPassword(prompt fmt.Stringer) ([]byte, error) {
	return i.Operation.Password(prompt)
}

type Result struct {
	Line  string
	Error error
}

func (l *Result) CanContinue() bool {
	return len(l.Line) != 0 && l.Error == ErrInterrupt
}

func (l *Result) CanBreak() bool {
	return !l.CanContinue() && l.Error != nil
}

func (i *Instance) Line() *Result {
	ret, err := i.Readline()
	return &Result{ret, err}
}

// err is one of (nil, io.EOF, readline.ErrInterrupt)
func (i *Instance) Readline() (string, error) {
	return i.Operation.String()
}

func (i *Instance) ReadlineWithDefault(what string) (string, error) {
	i.Operation.SetBuffer(what)
	return i.Operation.String()
}

func (i *Instance) SaveHistory(content string) error {
	return i.Operation.SaveHistory(content)
}

// same as readline
func (i *Instance) ReadSlice() ([]byte, error) {
	return i.Operation.Slice()
}

// we must make sure that call Close() before process exit.
func (i *Instance) Close() error {
	if err := i.Terminal.Close(); err != nil {
		return err
	}
	i.Config.Stdin.Close()
	i.Operation.Close()
	return nil
}
func (i *Instance) Clean() {
	i.Operation.Clean()
}

func (i *Instance) Write(b []byte) (int, error) {
	return i.Stdout().Write(b)
}

// WriteStdin prefill the next Stdin fetch
// Next time you call ReadLine() this value will be writen before the user input
// ie :
//  i := readline.New()
//  i.WriteStdin([]byte("test"))
//  _, _= i.Readline()
//
// gives
//
// > test[cursor]
func (i *Instance) WriteStdin(val []byte) (int, error) {
	return i.Terminal.WriteStdin(val)
}

func (i *Instance) SetConfig(cfg *Config) *Config {
	if i.Config == cfg {
		return cfg
	}
	old := i.Config
	i.Config = cfg
	i.Operation.SetConfig(cfg)
	i.Terminal.SetConfig(cfg)
	return old
}

func (i *Instance) Refresh() {
	i.Operation.Refresh()
}

// HistoryDisable the save of the commands into the history
func (i *Instance) HistoryDisable() {
	i.Operation.history.Disable()
}

// HistoryEnable the save of the commands into the history (default on)
func (i *Instance) HistoryEnable() {
	i.Operation.history.Enable()
}