package internal

import (
	"bufio"
	"errors"
	"io"
	"os"
	"path/filepath"

	"github.com/ergochat/readline"

	"github.com/sipeed/picoclaw/pkg/config"
	"github.com/sipeed/picoclaw/pkg/logger"
)

// 错误定义
var (
	ErrInterrupt = errors.New("interrupt")
	ErrEOF       = errors.New("EOF")
)

// Logo 是 hxclaw 的 Logo
const Logo = "🦐"

// GetPicoclawHome 返回 picoclaw 的家目录
// 优先级: $PICOCLAW_HOME > ~/.picoclaw
func GetPicoclawHome() string {
	return config.GetHome()
}

// LoadConfig 加载配置文件
// 复用 picoclaw 的配置加载逻辑
func LoadConfig() (*config.Config, error) {
	cfg, err := config.LoadConfig(GetConfigPath())
	if err != nil {
		return nil, err
	}
	logger.SetLevelFromString(cfg.Gateway.LogLevel)
	return cfg, nil
}

// GetConfigPath 获取配置文件路径
func GetConfigPath() string {
	if configPath := os.Getenv(config.EnvConfig); configPath != "" {
		return configPath
	}
	return filepath.Join(GetPicoclawHome(), "config.json")
}

// Readline 实例包装
type Readline struct {
	rl *readline.Instance
}

// NewReadline 创建一个新的 Readline 实例
func NewReadline(prompt string) (*Readline, error) {
	// 确保历史文件目录存在
	historyDir := filepath.Dir(filepath.Join(GetPicoclawHome(), ".hxclaw_history"))
	os.MkdirAll(historyDir, 0755)

	rl, err := readline.NewEx(&readline.Config{
		Prompt:          prompt,
		HistoryFile:     filepath.Join(GetPicoclawHome(), ".hxclaw_history"),
		HistoryLimit:    100,
		InterruptPrompt: "^C",
		EOFPrompt:       "exit",
	})
	if err != nil {
		return nil, err
	}
	return &Readline{rl: rl}, nil
}

// Readline 读取一行输入
func (r *Readline) Readline() (string, error) {
	line, err := r.rl.Readline()
	if err != nil {
		if err == readline.ErrInterrupt {
			return "", ErrInterrupt
		}
		if err == io.EOF {
			return "", ErrEOF
		}
		return "", err
	}
	return line, nil
}

// Close 关闭 Readline 实例
func (r *Readline) Close() error {
	return r.rl.Close()
}

// SimpleReader 简单输入读取器（无历史记录）
type SimpleReader struct {
	reader *bufio.Reader
}

// NewSimpleReader 创建一个新的简单读取器
func NewSimpleReader() *SimpleReader {
	return &SimpleReader{
		reader: bufio.NewReader(os.Stdin),
	}
}

// ReadString 读取一行输入
func (r *SimpleReader) ReadString() (string, error) {
	line, err := r.reader.ReadString('\n')
	if err != nil {
		if err == io.EOF {
			return "", ErrEOF
		}
		return "", err
	}
	// 去掉换行符
	if len(line) > 0 && line[len(line)-1] == '\n' {
		line = line[:len(line)-1]
	}
	return line, nil
}

func FindParagraphEnd(text string, startPos int) int {
	if startPos >= len(text) {
		return 0
	}

	inCodeBlock := false
	inMathBlock := false

	for i := startPos; i < len(text); i++ {
		if i+3 < len(text) && text[i:i+3] == "```" {
			if !inCodeBlock {
				inCodeBlock = true
			} else {
				inCodeBlock = false
			}
			continue
		}

		if i+2 < len(text) && (text[i:i+2] == "$$" || text[i:i+2] == "\\[") {
			inMathBlock = !inMathBlock
			continue
		}

		if inCodeBlock || inMathBlock {
			continue
		}

		if i+1 < len(text) && text[i] == '\n' && text[i+1] == '\n' {
			return i + 2
		}
	}

	return 0
}