package main

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/joho/godotenv"
	"github.com/streadway/amqp"
)

type JobCompletionMessage struct {
	JobID           string  `json:"job_id"`
	InputPath       string  `json:"input_path"`
	OutputPath      string  `json:"output_path"`
	ProcessingTime  float64 `json:"processing_time_seconds"`
	Status          string  `json:"status"`
	Timestamp       string  `json:"timestamp"`
	FileSize        int64   `json:"file_size,omitempty"`
	ImageDimensions string  `json:"image_dimensions,omitempty"`
	ErrorMessage    string  `json:"error_message,omitempty"`
}

type ProcessedImageRecord struct {
	JobID           string    `json:"job_id"`
	InputPath       string    `json:"input_path"`
	OutputPath      string    `json:"output_path"`
	SHA256Hash      string    `json:"sha256_hash"`
	FileSize        int64     `json:"file_size"`
	ImageDimensions string    `json:"image_dimensions"`
	ProcessingTime  float64   `json:"processing_time_seconds"`
	Status          string    `json:"status"`
	CreatedAt       time.Time `json:"created_at"`
	UpdatedAt       time.Time `json:"updated_at"`
	ErrorMessage    string    `json:"error_message,omitempty"`
}

func calculateSHA256(filePath string) (string, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return "", fmt.Errorf("failed to open file: %v", err)
	}
	defer file.Close()

	hasher := sha256.New()
	if _, err := io.Copy(hasher, file); err != nil {
		return "", fmt.Errorf("failed to calculate hash: %v", err)
	}

	return hex.EncodeToString(hasher.Sum(nil)), nil
}

func processCompletionMessage(msg JobCompletionMessage) error {
	log.Printf("Processing completion message for job: %s", msg.JobID)

	// Create the processed image record
	record := ProcessedImageRecord{
		JobID:           msg.JobID,
		InputPath:       msg.InputPath,
		OutputPath:      msg.OutputPath,
		FileSize:        msg.FileSize,
		ImageDimensions: msg.ImageDimensions,
		ProcessingTime:  msg.ProcessingTime,
		Status:          msg.Status,
		CreatedAt:       time.Now(),
		UpdatedAt:       time.Now(),
		ErrorMessage:    msg.ErrorMessage,
	}

	// If the job completed successfully, calculate SHA256
	if msg.Status == "completed" && msg.OutputPath != "" {
		hash, err := calculateSHA256(msg.OutputPath)
		if err != nil {
			log.Printf("Failed to calculate SHA256 for %s: %v", msg.OutputPath, err)
			record.Status = "hash_calculation_failed"
			record.ErrorMessage = fmt.Sprintf("SHA256 calculation failed: %v", err)
		} else {
			record.SHA256Hash = hash
			log.Printf("Calculated SHA256 for %s: %s", msg.OutputPath, hash)
		}
	}

	// Here you would typically save to a database
	// For now, we'll just log and save to a JSON file as an example
	return saveToDatabase(record)
}

func saveToDatabase(record ProcessedImageRecord) error {
	// TODO: Replace this with actual database integration
	// This is just a placeholder that saves to a JSON file
	
	// Create logs directory if it doesn't exist
	if err := os.MkdirAll("./logs", 0755); err != nil {
		return fmt.Errorf("failed to create logs directory: %v", err)
	}

	// Append to a JSON lines file
	file, err := os.OpenFile("./logs/processed_images.jsonl", os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
	if err != nil {
		return fmt.Errorf("failed to open log file: %v", err)
	}
	defer file.Close()

	// Marshal record to JSON
	data, err := json.Marshal(record)
	if err != nil {
		return fmt.Errorf("failed to marshal record: %v", err)
	}

	// Write to file
	if _, err := file.Write(append(data, '\n')); err != nil {
		return fmt.Errorf("failed to write record: %v", err)
	}

	log.Printf("Saved record for job %s to database", record.JobID)
	return nil
}

func consumeJobCompletions() {
	rabbitURL := os.Getenv("RABBITMQ_URL")
	if rabbitURL == "" {
		log.Println("RABBITMQ_URL not set, using default")
		rabbitURL = "amqp://guest:guest@rabbitmq:5672/"
	} else {
		log.Println("Using RabbitMQ URL:", rabbitURL)
	}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	for {
		select {
		case <-ctx.Done():
			fmt.Println("Shutting down job completion consumer...")
			return
		default:
			conn, err := amqp.Dial(rabbitURL)
			if err != nil {
				fmt.Println("Failed to connect to RabbitMQ:", err)
				time.Sleep(5 * time.Second)
				continue
			}
			defer conn.Close()

			ch, err := conn.Channel()
			if err != nil {
				fmt.Println("Failed to open RabbitMQ channel:", err)
				time.Sleep(5 * time.Second)
				continue
			}
			defer ch.Close()

			// Declare the job_completions queue
			q, err := ch.QueueDeclare(
				"job_completions",
				true,  
				false,
				false,
				false,
				nil,
			)
			if err != nil {
				fmt.Println("Queue declare failed:", err)
				time.Sleep(5 * time.Second)
				continue
			}

			// Set QoS to process one message at a time
			err = ch.Qos(
				1,     
				0,    
				false, 
			)
			if err != nil {
				fmt.Println("Failed to set QoS:", err)
				time.Sleep(5 * time.Second)
				continue
			}

			msgs, err := ch.Consume(
				q.Name,
				"completion-consumer", 
				false,                 
				false,                 
				false,                 
				false,                 
				nil,
			)
			if err != nil {
				fmt.Println("Queue consume failed:", err)
				time.Sleep(5 * time.Second)
				continue
			}

			fmt.Println("Job completion consumer started...")
			for d := range msgs {
				var completionMsg JobCompletionMessage
				if err := json.Unmarshal(d.Body, &completionMsg); err != nil {
					log.Printf("Invalid completion message payload: %v", err)
					d.Nack(false, false) // discard the message
					continue
				}

				if err := processCompletionMessage(completionMsg); err != nil {
					log.Printf("Failed to process completion message: %v", err)
					d.Nack(false, true) 
					continue
				}

				d.Ack(false)
			}

			fmt.Println("Job completion consumer disconnected. Reconnecting...")
			time.Sleep(5 * time.Second)
		}
	}
}

func main() {
	// Load environment variables
	err := godotenv.Load()
	if err != nil {
		log.Println(".env file not found or could not be loaded")
	}

	fmt.Println("Starting Image Processing Completion Consumer")
	fmt.Println("===========================================")
	fmt.Printf("Consumer will process job completion messages from 'job_completions' queue\n")
	fmt.Printf("Processed records will be saved to: ./logs/processed_images.jsonl\n\n")

	// Start consuming job completion messages
	consumeJobCompletions()
}