package api

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sync"
	"time"
	"unicode/utf8"

	"github.com/muyue/muyue/internal/config"
)

const shellMaxTokens = 100000
const shellCharsPerToken = 4

type ShellMessage struct {
	ID      string `json:"id"`
	Role    string `json:"role"`
	Content string `json:"content"`
	Time    string `json:"time"`
}

type ShellConvStore struct {
	mu   sync.RWMutex
	path string
	msgs []ShellMessage
}

func NewShellConvStore() *ShellConvStore {
	dir, err := config.ConfigDir()
	if err != nil {
		dir = "/tmp/muyue"
	}
	path := filepath.Join(dir, "shell_conversation.json")
	s := &ShellConvStore{path: path}
	s.load()
	return s
}

func (s *ShellConvStore) load() {
	data, err := os.ReadFile(s.path)
	if err != nil {
		s.msgs = []ShellMessage{}
		return
	}
	json.Unmarshal(data, &s.msgs)
	if s.msgs == nil {
		s.msgs = []ShellMessage{}
	}
}

func (s *ShellConvStore) save() {
	data, _ := json.MarshalIndent(s.msgs, "", "  ")
	os.MkdirAll(filepath.Dir(s.path), 0755)
	os.WriteFile(s.path, data, 0600)
}

func (s *ShellConvStore) Get() []ShellMessage {
	s.mu.RLock()
	defer s.mu.RUnlock()
	out := make([]ShellMessage, len(s.msgs))
	copy(out, s.msgs)
	return out
}

func (s *ShellConvStore) Add(role, content string) ShellMessage {
	s.mu.Lock()
	defer s.mu.Unlock()
	msg := ShellMessage{
		ID:      time.Now().Format("20060102150405.000"),
		Role:    role,
		Content: content,
		Time:    time.Now().Format(time.RFC3339),
	}
	s.msgs = append(s.msgs, msg)
	s.save()
	return msg
}

func (s *ShellConvStore) Clear() {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.msgs = []ShellMessage{}
	s.save()
}

func (s *ShellConvStore) ApproxTokens() int {
	s.mu.RLock()
	defer s.mu.RUnlock()
	total := 0
	for _, m := range s.msgs {
		total += utf8.RuneCountInString(m.Content) / shellCharsPerToken
	}
	return total
}

func (s *ShellConvStore) AtLimit() bool {
	return s.ApproxTokens() >= shellMaxTokens
}

func LoadSystemAnalysis() string {
	dir, err := config.ConfigDir()
	if err != nil {
		return ""
	}
	data, err := os.ReadFile(filepath.Join(dir, "system_analysis.md"))
	if err != nil {
		return ""
	}
	return string(data)
}

func SaveSystemAnalysis(content string) error {
	dir, err := config.ConfigDir()
	if err != nil {
		return err
	}
	os.MkdirAll(dir, 0755)
	return os.WriteFile(filepath.Join(dir, "system_analysis.md"), []byte(content), 0644)
}