package core

// 推送历史：记住「哪些画廊被推送过」，与任务列表解耦
//
// 为什么单独存一份：
//
//	state.json 里的 tasks 是「当前要下载的东西」，用户点「清除已完成」就会删掉。
//	但「这个画廊我推送过」是个历史事实，删了任务不该忘掉 ——
//	油猴脚本靠它把标题标灰，让你刷新后还认得出哪些推过。
//
// 所以单独一个 pushed.json，放在和 state.json 同一个目录（%APPDATA%\EH Downloader\）。
// 只有 gid 是必须的，token/title 留着方便排查。
//
// 清理方式：删掉 pushed.json 即可；或者在设置里提供「清空推送历史」。

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sort"
	"sync"
	"time"
)

// PushedEntry 一条推送记录
type PushedEntry struct {
	GID       string `json:"gid"`
	Token     string `json:"token,omitempty"`
	Title     string `json:"title,omitempty"`
	PushedAt  int64  `json:"pushedAt"`
	Completed bool   `json:"completed,omitempty"` // 曾经下载完成过
}

// PushedState pushed.json 的顶层结构
type PushedState struct {
	Entries []PushedEntry `json:"entries"`
}

// PushedStore 推送历史存储
type PushedStore struct {
	mu    sync.RWMutex
	path  string
	state PushedState

	flushTimer *time.Timer
}

// NewPushedStore 打开（或新建）推送历史文件
func NewPushedStore(filePath string) *PushedStore {
	p := &PushedStore{path: filePath}
	p.load()
	return p
}

func (p *PushedStore) load() {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.state = PushedState{Entries: []PushedEntry{}}

	raw, err := os.ReadFile(p.path)
	if err != nil {
		return
	}
	var loaded PushedState
	if json.Unmarshal(raw, &loaded) == nil {
		if loaded.Entries == nil {
			loaded.Entries = []PushedEntry{}
		}
		p.state = loaded
	}
}

// Flush 原子写
func (p *PushedStore) Flush() {
	p.mu.RLock()
	data, err := json.MarshalIndent(p.state, "", "  ")
	path := p.path
	p.mu.RUnlock()

	if err != nil {
		return
	}
	tmp := path + ".tmp"
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return
	}
	if err := os.WriteFile(tmp, data, 0o644); err != nil {
		return
	}
	_ = os.Rename(tmp, path)
}

// ScheduleFlush 合并短时间内的多次写
func (p *PushedStore) ScheduleFlush(delay int) {
	if delay <= 0 {
		delay = 400
	}
	p.mu.Lock()
	defer p.mu.Unlock()
	if p.flushTimer != nil {
		return
	}
	p.flushTimer = time.AfterFunc(time.Duration(delay)*time.Millisecond, func() {
		p.mu.Lock()
		p.flushTimer = nil
		p.mu.Unlock()
		p.Flush()
	})
}

// Stop 停掉待执行的延迟写
func (p *PushedStore) Stop() {
	p.mu.Lock()
	if p.flushTimer != nil {
		p.flushTimer.Stop()
		p.flushTimer = nil
	}
	p.mu.Unlock()
}

// Mark 记一笔推送（同 gid 重复推送只更新时间，不重复添加）
func (p *PushedStore) Mark(gid, token, title string) {
	gid = trim(gid)
	if gid == "" {
		return
	}
	p.mu.Lock()
	for i := range p.state.Entries {
		if p.state.Entries[i].GID == gid {
			if token != "" {
				p.state.Entries[i].Token = token
			}
			if title != "" {
				p.state.Entries[i].Title = title
			}
			p.state.Entries[i].PushedAt = time.Now().Unix()
			p.mu.Unlock()
			p.ScheduleFlush(0)
			return
		}
	}
	p.state.Entries = append(p.state.Entries, PushedEntry{
		GID:      gid,
		Token:    token,
		Title:    title,
		PushedAt: time.Now().Unix(),
	})
	p.mu.Unlock()
	p.ScheduleFlush(0)
}

// MarkBatch 批量记
func (p *PushedStore) MarkBatch(items []PushedEntry) {
	if len(items) == 0 {
		return
	}
	p.mu.Lock()
	now := time.Now().Unix()
	idx := map[string]int{}
	for i := range p.state.Entries {
		idx[p.state.Entries[i].GID] = i
	}
	for _, it := range items {
		gid := trim(it.GID)
		if gid == "" {
			continue
		}
		if i, ok := idx[gid]; ok {
			p.state.Entries[i].Token = it.Token
			p.state.Entries[i].Title = it.Title
			p.state.Entries[i].PushedAt = now
			continue
		}
		idx[gid] = len(p.state.Entries)
		p.state.Entries = append(p.state.Entries, PushedEntry{
			GID: gid, Token: it.Token, Title: it.Title, PushedAt: now,
		})
	}
	p.mu.Unlock()
	p.ScheduleFlush(0)
}

// MarkCompleted 标记某画廊已下载完成（只打标，不删记录）
func (p *PushedStore) MarkCompleted(gid string) {
	gid = trim(gid)
	if gid == "" {
		return
	}
	p.mu.Lock()
	found := false
	for i := range p.state.Entries {
		if p.state.Entries[i].GID == gid {
			p.state.Entries[i].Completed = true
			found = true
			break
		}
	}
	p.mu.Unlock()
	if found {
		p.ScheduleFlush(0)
	}
}

// GIDs 取全部推送过的 gid
func (p *PushedStore) GIDs() []string {
	p.mu.RLock()
	defer p.mu.RUnlock()
	out := make([]string, 0, len(p.state.Entries))
	for _, e := range p.state.Entries {
		out = append(out, e.GID)
	}
	return out
}

// Entries 取全部记录（按推送时间倒序，新的在前）
func (p *PushedStore) Entries() []PushedEntry {
	p.mu.RLock()
	defer p.mu.RUnlock()
	out := make([]PushedEntry, len(p.state.Entries))
	copy(out, p.state.Entries)
	sort.SliceStable(out, func(i, j int) bool { return out[i].PushedAt > out[j].PushedAt })
	return out
}

// Count 记录条数
func (p *PushedStore) Count() int {
	p.mu.RLock()
	defer p.mu.RUnlock()
	return len(p.state.Entries)
}

// Clear 清空推送历史
func (p *PushedStore) Clear() {
	p.mu.Lock()
	p.state = PushedState{Entries: []PushedEntry{}}
	p.mu.Unlock()
	p.ScheduleFlush(0)
}

// trim 去空白
func trim(s string) string {
	start, end := 0, len(s)
	for start < end && (s[start] == ' ' || s[start] == '\t' || s[start] == '\n' || s[start] == '\r') {
		start++
	}
	for end > start && (s[end-1] == ' ' || s[end-1] == '\t' || s[end-1] == '\n' || s[end-1] == '\r') {
		end--
	}
	return s[start:end]
}