package server

import (
	"errors"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"code.littlelan.cn/CarrotAssistant/backend/internal/security"
	"code.littlelan.cn/CarrotAssistant/backend/internal/store"
)

type appReq struct {
	Slug          string `json:"slug"`
	Name          string `json:"name" binding:"required"`
	Description   string `json:"description"`
	ModelConfigID *int64 `json:"model_config_id"`
	Status        string `json:"status"`
}

// GET /admin/apps
func (d Deps) handleListApps(c *gin.Context) {
	var apps []store.App
	d.DB.Order("id DESC").Find(&apps)
	c.JSON(http.StatusOK, apps)
}

// GET /admin/apps/:id
func (d Deps) handleGetApp(c *gin.Context) {
	a, ok := d.loadApp(c)
	if !ok {
		return
	}
	c.JSON(http.StatusOK, a)
}

// POST /admin/apps — slug auto-derived from name when omitted. A fresh
// access token is generated and returned ONCE in the response; only its hash
// is persisted, so the operator must save it immediately.
func (d Deps) handleCreateApp(c *gin.Context) {
	var req appReq
	if !bind(c, &req) {
		return
	}
	slug := security.Slugify(req.Slug)
	if slug == "" {
		slug = security.Slugify(req.Name)
	}
	if slug == "" {
		// Name had no ASCII slug chars (e.g. pure CJK). Derive a short random
		// slug so the app is still addressable on disk and in URLs.
		slug = security.RandomSlug()
	}

	// Ensure slug uniqueness.
	var existing store.App
	err := d.DB.Where("slug = ?", slug).First(&existing).Error
	if err == nil {
		c.JSON(http.StatusConflict, gin.H{"error": "slug 已存在"})
		return
	}
	if !errors.Is(err, gorm.ErrRecordNotFound) {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "查询失败"})
		return
	}

	token, err := security.GenerateToken("ca")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "生成 token 失败"})
		return
	}
	status := strings.TrimSpace(req.Status)
	if status == "" {
		status = "active"
	}
	a := store.App{
		Slug:          slug,
		Name:          req.Name,
		Description:   req.Description,
		TokenHash:     security.HashToken(token),
		ModelConfigID: req.ModelConfigID,
		Status:        status,
	}
	if err := d.DB.Create(&a).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "创建失败"})
		return
	}
	d.audit(c, &a.ID, nil, "app.create", map[string]any{"slug": a.Slug})

	// Plain token is returned only here; subsequent reads only have the hash.
	c.JSON(http.StatusOK, gin.H{
		"app":   a,
		"token": token,
	})
}

// PUT /admin/apps/:id — updates mutable fields. Slug is intentionally not
// editable post-create because skills live under <SkillsDir>/<slug>/ and a
// rename would orphan them.
func (d Deps) handleUpdateApp(c *gin.Context) {
	a, ok := d.loadApp(c)
	if !ok {
		return
	}
	var req appReq
	if !bind(c, &req) {
		return
	}
	a.Name = req.Name
	a.Description = req.Description
	a.ModelConfigID = req.ModelConfigID
	if s := strings.TrimSpace(req.Status); s != "" {
		a.Status = s
	}
	if err := d.DB.Save(a).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "保存失败"})
		return
	}
	d.audit(c, &a.ID, nil, "app.update", nil)
	c.JSON(http.StatusOK, a)
}

// DELETE /admin/apps/:id — cascades to skills (rows + their markdown files),
// sessions, and messages. Wrapped in a transaction so a partial failure
// leaves the app intact.
func (d Deps) handleDeleteApp(c *gin.Context) {
	a, ok := d.loadApp(c)
	if !ok {
		return
	}
	err := d.DB.Transaction(func(tx *gorm.DB) error {
		// Collect skill file paths so we can remove them on disk after the
		// transaction commits.
		var skills []store.Skill
		tx.Where("app_id = ?", a.ID).Find(&skills)
		if err := tx.Where("app_id = ?", a.ID).Delete(&store.Skill{}).Error; err != nil {
			return err
		}
		// Delete messages that belong to this app's sessions, then sessions.
		tx.Where("session_id IN (SELECT id FROM sessions WHERE app_id = ?)", a.ID).Delete(&store.Message{})
		if err := tx.Where("app_id = ?", a.ID).Delete(&store.Session{}).Error; err != nil {
			return err
		}
		return tx.Delete(a).Error
	})
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "删除失败"})
		return
	}
	// Best-effort: remove the app's skill directory on disk.
	removeAppSkillDir(d.SkillsDir, a.Slug)
	d.audit(c, &a.ID, nil, "app.delete", map[string]any{"slug": a.Slug})
	c.JSON(http.StatusOK, gin.H{"ok": true})
}

// POST /admin/apps/:id/token/rotate — invalidates the old token and returns a
// new plaintext token once.
func (d Deps) handleRotateToken(c *gin.Context) {
	a, ok := d.loadApp(c)
	if !ok {
		return
	}
	token, err := security.GenerateToken("ca")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "生成 token 失败"})
		return
	}
	a.TokenHash = security.HashToken(token)
	if err := d.DB.Save(a).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "保存失败"})
		return
	}
	d.audit(c, &a.ID, nil, "app.token_rotate", nil)
	c.JSON(http.StatusOK, gin.H{"token": token})
}

// loadApp fetches :id and writes a 404 on miss. Returns the app and true on
// success so handlers can `if !ok { return }` at the top.
func (d Deps) loadApp(c *gin.Context) (*store.App, bool) {
	id := c.Param("id")
	var a store.App
	if err := d.DB.First(&a, "id = ?", id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			c.JSON(http.StatusNotFound, gin.H{"error": "应用未找到"})
			return nil, false
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "查询失败"})
		return nil, false
	}
	return &a, true
}