package main

import (
	"encoding/json"
	"errors"
	"net/http"

	"github.com/gorilla/mux"
	"github.com/mattermost/mattermost/server/public/plugin"
)

type cleanupRequest struct {
	ChannelID string `json:"channel_id"`
}

type cleanupResponse struct {
	Deleted int `json:"deleted"`
}

type autoCleanupRequest struct {
	ChannelID  string `json:"channel_id"`
	OffsetDays int    `json:"offset_days"`
}

type autoCleanupResponse struct {
	ChannelID  string `json:"channel_id"`
	OffsetDays int    `json:"offset_days"`
	Enabled    bool   `json:"enabled"`
}

func (p *Plugin) initRouter() *mux.Router {
	router := mux.NewRouter()
	router.Use(p.requireLoggedInUser)

	apiRouter := router.PathPrefix("/api/v1").Subrouter()
	apiRouter.HandleFunc("/cleanup", p.handleCleanup).Methods(http.MethodPost)
	apiRouter.HandleFunc("/auto-cleanup/run", p.handleRunAutoCleanup).Methods(http.MethodPost)
	apiRouter.HandleFunc("/auto-cleanup", p.handleSetAutoCleanup).Methods(http.MethodPut)
	apiRouter.HandleFunc("/auto-cleanup/{channel_id}", p.handleGetAutoCleanup).Methods(http.MethodGet)
	apiRouter.HandleFunc("/auto-cleanup/{channel_id}", p.handleDeleteAutoCleanup).Methods(http.MethodDelete)

	return router
}

func (p *Plugin) ServeHTTP(_ *plugin.Context, w http.ResponseWriter, r *http.Request) {
	p.router.ServeHTTP(w, r)
}

func (p *Plugin) requireLoggedInUser(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Header.Get("Mattermost-User-ID") == "" {
			http.Error(w, "Not authorized", http.StatusUnauthorized)
			return
		}

		next.ServeHTTP(w, r)
	})
}

func (p *Plugin) handleCleanup(w http.ResponseWriter, r *http.Request) {
	userID := r.Header.Get("Mattermost-User-ID")

	var req cleanupRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}
	if req.ChannelID == "" {
		http.Error(w, "channel_id is required", http.StatusBadRequest)
		return
	}

	deleted, err := p.cleanupChannel(userID, req.ChannelID)
	if err != nil {
		if errors.Is(err, errPermissionDenied) {
			http.Error(w, err.Error(), http.StatusForbidden)
			return
		}

		p.client.Log.Error("Failed to cleanup channel", "channel_id", req.ChannelID, "error", err)
		http.Error(w, "Failed to cleanup channel", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(cleanupResponse{Deleted: deleted}); err != nil {
		p.client.Log.Error("Failed to encode cleanup response", "error", err)
	}
}

type autoCleanupRunRequest struct {
	ChannelID  string `json:"channel_id"`
	OffsetDays int    `json:"offset_days,omitempty"`
}

func (p *Plugin) handleRunAutoCleanup(w http.ResponseWriter, r *http.Request) {
	userID := r.Header.Get("Mattermost-User-ID")
	if !p.isSystemAdmin(userID) {
		http.Error(w, errPermissionDenied.Error(), http.StatusForbidden)
		return
	}

	var req autoCleanupRunRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}
	if req.ChannelID == "" {
		http.Error(w, "channel_id is required", http.StatusBadRequest)
		return
	}

	offsetDays := req.OffsetDays
	if offsetDays <= 0 {
		config, err := p.autoCleanupStore.Get(req.ChannelID)
		if err != nil {
			p.client.Log.Error("Failed to get auto cleanup config", "channel_id", req.ChannelID, "error", err)
			http.Error(w, "Failed to get auto cleanup config", http.StatusInternalServerError)
			return
		}
		if config == nil {
			http.Error(w, "automatic cleanup is not configured for this channel", http.StatusBadRequest)
			return
		}
		offsetDays = config.OffsetDays
	}

	deleted, err := p.autoCleanupChannel(req.ChannelID, offsetDays)
	if err != nil {
		p.client.Log.Error("Failed to run auto cleanup", "channel_id", req.ChannelID, "error", err)
		http.Error(w, "Failed to run auto cleanup", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(cleanupResponse{Deleted: deleted}); err != nil {
		p.client.Log.Error("Failed to encode auto cleanup run response", "error", err)
	}
}

func (p *Plugin) handleGetAutoCleanup(w http.ResponseWriter, r *http.Request) {
	userID := r.Header.Get("Mattermost-User-ID")
	if !p.isSystemAdmin(userID) {
		http.Error(w, errPermissionDenied.Error(), http.StatusForbidden)
		return
	}

	channelID := mux.Vars(r)["channel_id"]
	if channelID == "" {
		http.Error(w, "channel_id is required", http.StatusBadRequest)
		return
	}

	config, err := p.autoCleanupStore.Get(channelID)
	if err != nil {
		p.client.Log.Error("Failed to get auto cleanup config", "channel_id", channelID, "error", err)
		http.Error(w, "Failed to get auto cleanup config", http.StatusInternalServerError)
		return
	}

	response := autoCleanupResponse{
		ChannelID: channelID,
		Enabled:   config != nil,
	}
	if config != nil {
		response.OffsetDays = config.OffsetDays
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(response); err != nil {
		p.client.Log.Error("Failed to encode auto cleanup response", "error", err)
	}
}

func (p *Plugin) handleSetAutoCleanup(w http.ResponseWriter, r *http.Request) {
	userID := r.Header.Get("Mattermost-User-ID")
	if !p.isSystemAdmin(userID) {
		http.Error(w, errPermissionDenied.Error(), http.StatusForbidden)
		return
	}

	var req autoCleanupRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}
	if req.ChannelID == "" {
		http.Error(w, "channel_id is required", http.StatusBadRequest)
		return
	}
	if req.OffsetDays <= 0 {
		http.Error(w, "offset_days must be greater than zero", http.StatusBadRequest)
		return
	}

	if _, err := p.client.Channel.Get(req.ChannelID); err != nil {
		http.Error(w, "channel not found", http.StatusNotFound)
		return
	}

	if err := p.autoCleanupStore.Set(req.ChannelID, req.OffsetDays); err != nil {
		p.client.Log.Error("Failed to set auto cleanup config", "channel_id", req.ChannelID, "error", err)
		http.Error(w, "Failed to set auto cleanup config", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(autoCleanupResponse{
		ChannelID:  req.ChannelID,
		OffsetDays: req.OffsetDays,
		Enabled:    true,
	}); err != nil {
		p.client.Log.Error("Failed to encode auto cleanup response", "error", err)
	}
}

func (p *Plugin) handleDeleteAutoCleanup(w http.ResponseWriter, r *http.Request) {
	userID := r.Header.Get("Mattermost-User-ID")
	if !p.isSystemAdmin(userID) {
		http.Error(w, errPermissionDenied.Error(), http.StatusForbidden)
		return
	}

	channelID := mux.Vars(r)["channel_id"]
	if channelID == "" {
		http.Error(w, "channel_id is required", http.StatusBadRequest)
		return
	}

	if err := p.autoCleanupStore.Delete(channelID); err != nil {
		p.client.Log.Error("Failed to delete auto cleanup config", "channel_id", channelID, "error", err)
		http.Error(w, "Failed to delete auto cleanup config", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(autoCleanupResponse{
		ChannelID: channelID,
		Enabled:   false,
	}); err != nil {
		p.client.Log.Error("Failed to encode auto cleanup response", "error", err)
	}
}