// Copyright (c) 2025 Nikolai Papin
//
// This file is part of the Auto Attendance app that looks for
// self-attend QR-codes during lectures and opens their URLs in your
// browser.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
// the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package app

import (
	"context"
	"fmt"
	"sync"
	"sync/atomic"
	"time"

	"git.weirdcat.su/weirdcat/auto-attendance/internal/browserlauncher"
	"git.weirdcat.su/weirdcat/auto-attendance/internal/config"
	"git.weirdcat.su/weirdcat/auto-attendance/internal/linkvalidator"
	"git.weirdcat.su/weirdcat/auto-attendance/internal/logger"
	"git.weirdcat.su/weirdcat/auto-attendance/internal/screencapturer"
	"git.weirdcat.su/weirdcat/auto-attendance/internal/vision"
	"go.uber.org/fx"
)

type App interface {
	Init() error
	Start() error
	Stop() error
	Toggle() error
	ConsoleOutput() (string, error)
	UpdateConfig(string) error
}

type appImpl struct {
	config    *config.Config
	log       *logger.Logger
	capturer  screencapturer.ScreenCapturer
	vision    vision.Vision
	validator linkvalidator.LinkValidator
	launcher  browserlauncher.BrowserLauncher

	active     atomic.Bool
	stats      Stats
	mu         sync.RWMutex
	ctx        context.Context
	cancel     context.CancelFunc
	wg         sync.WaitGroup
	startTime  time.Time
	foundCount int
	consoleBuf []string
	consoleMu  sync.RWMutex
}

// ConsoleOutput implements App.
func (a *appImpl) ConsoleOutput() (string, error) {
	a.consoleMu.RLock()
	defer a.consoleMu.RUnlock()

	if len(a.consoleBuf) == 0 {
		return "", nil
	}

	output := ""
	for _, line := range a.consoleBuf {
		output += line + "\n"
	}
	return output, nil
}

// Init implements App.
func (a *appImpl) Init() error {
	// Initialize screen capturer
	if err := a.capturer.Init(); err != nil {
		a.log.Error("Failed to initialize screen capturer", "error", err)
		return err
	}

	a.ctx, a.cancel = context.WithCancel(context.Background())
	a.stats.Status = Offline
	a.consoleBuf = make([]string, 0, 100)

	a.addConsoleOutput("Application initialized successfully")
	return nil
}

// Start implements App.
func (a *appImpl) Start() error {
	a.mu.Lock()
	defer a.mu.Unlock()

	if a.active.Load() {
		a.log.Warn("Application is already running")
		return fmt.Errorf("application is already running")
	}

	a.log.Info("Starting application")
	a.active.Store(true)
	a.startTime = time.Now()
	a.stats.Status = Waiting
	a.stats.FoundAmount = 0
	a.foundCount = 0

	a.wg.Add(1)
	go a.pollingLoop()

	a.addConsoleOutput("Application started - QR code monitoring active")
	a.log.Info("Application started successfully")
	return nil
}

// Stop implements App.
func (a *appImpl) Stop() error {
	a.mu.Lock()
	defer a.mu.Unlock()

	if !a.active.Load() {
		a.log.Warn("Application is not running")
		return fmt.Errorf("application is not running")
	}

	a.log.Info("Stopping application")
	a.active.Store(false)

	if a.cancel != nil {
		a.cancel()
	}

	a.wg.Wait()
	a.stats.Status = Offline
	a.stats.Uptime = time.Since(a.startTime)

	a.addConsoleOutput(fmt.Sprintf("Application stopped - Found %d QR codes", a.foundCount))
	a.log.Info("Application stopped successfully", "found_count", a.foundCount, "uptime", a.stats.Uptime)
	return nil
}

// Toggle implements App.
func (a *appImpl) Toggle() error {
	if a.active.Load() {
		return a.Stop()
	} else {
		return a.Start()
	}
}

// UpdateConfig implements App.
func (a *appImpl) UpdateConfig(configStr string) error {
	panic("not implemented")
}

func (a *appImpl) pollingLoop() {
	defer a.wg.Done()

	interval := time.Duration(a.config.Screenshot.Interval) * time.Second
	ticker := time.NewTicker(interval)
	defer ticker.Stop()

	a.log.Info("Polling loop started", "interval", interval)

	for {
		select {
		case <-a.ctx.Done():
			a.log.Debug("Polling loop stopped via context")
			return
		case <-ticker.C:
			if !a.active.Load() {
				continue
			}

			a.processScreenshot()

			// Check if we've reached the maximum number of links to open
			if a.foundCount >= a.config.App.LinksToOpenCount {
				a.log.Info("Reached maximum links to open, stopping", "max_links", a.config.App.LinksToOpenCount)
				a.Stop()
				return
			}
		}
	}
}

func (a *appImpl) processScreenshot() {
	a.stats.Status = Screenshotting

	// Capture screenshot
	filePath, err := a.capturer.Get()
	if err != nil {
		a.log.Error("Failed to capture screenshot", "error", err)
		a.addConsoleOutput("Error: Failed to capture screenshot")
		a.stats.Status = Waiting
		return
	}

	a.log.Debug("Screenshot captured", "path", filePath)

	// Analyze image for QR codes
	a.stats.Status = Analyzing
	visionData, err := a.vision.AnalyzeImage(filePath)
	if err != nil {
		a.log.Error("Failed to analyze image", "error", err)
		a.addConsoleOutput("Error: Failed to analyze screenshot for QR codes")
		a.stats.Status = Waiting
		return
	}

	if len(visionData) == 0 {
		a.log.Debug("No QR codes found in screenshot")
		a.stats.Status = Waiting
		return
	}

	a.log.Info("QR codes found in screenshot", "count", len(visionData))

	// Process each found QR code
	for _, data := range visionData {
		if !a.active.Load() {
			break
		}

		a.stats.Status = Validating
		a.stats.Link = data

		token, valid := a.validator.ValidateLink(data)
		if !valid {
			a.log.Debug("QR code content is not a valid link", "data", data)
			continue
		}

		a.log.Info("Valid QR code found", "token", token)
		a.addConsoleOutput(fmt.Sprintf("Valid QR code found: %s", data))

		// Open the link in browser if enabled
		if a.config.App.EnableLinkOpening {
			a.stats.Status = Completed
			if err := a.launcher.OpenAuto(data); err != nil {
				a.log.Error("Failed to open link in browser", "error", err)
				a.addConsoleOutput("Error: Failed to open link in browser")
			} else {
				a.log.Info("Link opened in browser successfully")
				a.addConsoleOutput("Link opened in browser successfully")
				a.foundCount++
				a.stats.FoundAmount = a.foundCount
			}
		} else {
			a.log.Info("Link opening is disabled in config")
			a.addConsoleOutput("Link opening is disabled - would have opened: " + data)
		}

		break
	}

	a.stats.Status = Waiting
	a.stats.Uptime = time.Since(a.startTime)
}

func (a *appImpl) addConsoleOutput(message string) {
	a.consoleMu.Lock()
	defer a.consoleMu.Unlock()

	timestamp := time.Now().Format("15:04:05")
	formattedMessage := fmt.Sprintf("[%s] %s", timestamp, message)

	if len(a.consoleBuf) >= 100 {
		a.consoleBuf = a.consoleBuf[1:]
	}
	a.consoleBuf = append(a.consoleBuf, formattedMessage)
}

func NewApp(
	lc fx.Lifecycle,
	cfg *config.Config,
	log *logger.Logger,
	capt screencapturer.ScreenCapturer,
	vis vision.Vision,
	val linkvalidator.LinkValidator,
	launch browserlauncher.BrowserLauncher,
) App {
	app := &appImpl{
		config:    cfg,
		log:       log,
		capturer:  capt,
		vision:    vis,
		validator: val,
		launcher:  launch,
		stats: Stats{
			Status:      Offline,
			Uptime:      0,
			FoundAmount: 0,
			Link:        "",
		},
	}

	lc.Append(fx.Hook{
		OnStop: func(ctx context.Context) error {
			log.Debug("stopping qrminator")
			return app.Stop()
		},
	})

	return app
}