// Package workers provides background goroutines for printer telemetry.
package workers

import (
	"context"
	"fmt"
	"log/slog"
	"strconv"
	"time"

	"github.com/CubeCraft-Creations/Extrudex/backend/internal/clients"
	"github.com/CubeCraft-Creations/Extrudex/backend/internal/models"
	"github.com/CubeCraft-Creations/Extrudex/backend/internal/repositories"
	"github.com/CubeCraft-Creations/Extrudex/backend/internal/sse"
	"github.com/jackc/pgx/v5/pgxpool"
)

// MoonrakerPollerConfig controls the background polling behaviour.
type MoonrakerPollerConfig struct {
	PollInterval   time.Duration
	RequestTimeout time.Duration
}

// DefaultMoonrakerPollerConfig returns sensible defaults.
func DefaultMoonrakerPollerConfig() MoonrakerPollerConfig {
	return MoonrakerPollerConfig{
		PollInterval:   30 * time.Second,
		RequestTimeout: 10 * time.Second,
	}
}

// MoonrakerPoller periodically polls Moonraker printers for status and usage.
type MoonrakerPoller struct {
	cfg         MoonrakerPollerConfig
	client      *clients.MoonrakerClient
	printerRepo *repositories.PrinterRepository
	jobRepo     *repositories.PrintJobRepository
	usageRepo   *repositories.UsageLogRepository
	sseBC       *sse.Broadcaster
	pool        *pgxpool.Pool
	stop        chan struct{}
}

// NewMoonrakerPoller creates a poller. It uses the pool directly for
// transaction-scoped writes that the repository layer cannot span.
func NewMoonrakerPoller(
	cfg MoonrakerPollerConfig,
	pool *pgxpool.Pool,
	printerRepo *repositories.PrinterRepository,
	jobRepo *repositories.PrintJobRepository,
	usageRepo *repositories.UsageLogRepository,
	sseBC *sse.Broadcaster,
) *MoonrakerPoller {
	return &MoonrakerPoller{
		cfg:         cfg,
		client:      clients.NewMoonrakerClient(cfg.RequestTimeout),
		printerRepo: printerRepo,
		jobRepo:     jobRepo,
		usageRepo:   usageRepo,
		sseBC:       sseBC,
		pool:        pool,
		stop:        make(chan struct{}),
	}
}

// Start begins the polling loop in a goroutine.
func (p *MoonrakerPoller) Start() {
	go p.loop()
}

// Stop signals the loop to exit.
func (p *MoonrakerPoller) Stop() {
	close(p.stop)
}

func (p *MoonrakerPoller) loop() {
	ticker := time.NewTicker(p.cfg.PollInterval)
	defer ticker.Stop()

	// Immediate first tick.
	p.pollCycle()

	for {
		select {
		case <-ticker.C:
			p.pollCycle()
		case <-p.stop:
			slog.Info("moonraker poller stopped")
			return
		}
	}
}

func (p *MoonrakerPoller) pollCycle() {
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
	defer cancel()

	printers, err := p.printerRepo.GetAll(ctx)
	if err != nil {
		slog.Error("moonraker poller: failed to list printers", "error", err)
		return
	}

	for _, printer := range printers {
		if !printer.IsActive || printer.MoonrakerURL == nil || *printer.MoonrakerURL == "" {
			continue
		}

		if err := p.pollPrinter(ctx, printer); err != nil {
			slog.Warn("moonraker poller: poll failed",
				"printer", printer.Name,
				"error", err,
			)
		}
	}
}

// pollPrinter performs a single Moonraker poll for a printer.
func (p *MoonrakerPoller) pollPrinter(ctx context.Context, printer models.Printer) error {
	host := *printer.MoonrakerURL
	var apiKey string
	if printer.MoonrakerAPIKey != nil {
		apiKey = *printer.MoonrakerAPIKey
	}

	// Fetch printer info (status)
	info, err := p.client.GetPrinterInfo(ctx, host, 80, apiKey)
	if err != nil {
		p.broadcastStatus(printer.ID, printer.Name, "offline")
		return err
	}

	status := mapMoonrakerState(info.State)
	p.broadcastStatus(printer.ID, printer.Name, status)

	// Fetch print stats
	stats, err := p.client.GetPrintStats(ctx, host, 80, apiKey)
	if err != nil {
		return fmt.Errorf("getPrintStats failed: %w", err)
	}

	if status == "printing" && stats.Filename != "" {
		p.broadcastJobStarted(printer.ID, stats.Filename)
	}

	if isCompleteState(stats.State) && stats.FilamentUsedMm > 0 {
		// Record usage
		if err := p.recordUsage(ctx, printer, stats); err != nil {
			slog.Error("moonraker poller: record usage failed",
				"printer", printer.Name, "error", err)
		} else {
			p.broadcastJobCompleted(printer.ID, stats.Filename, stats.FilamentUsedMm)
		}
	}

	return nil
}

func (p *MoonrakerPoller) recordUsage(ctx context.Context, printer models.Printer, stats *clients.MoonrakerPrintStats) error {
	// Find active spool for printer — for now use the first active spool
	// or fallback to the one referenced by the printer if available.
	// In a real scenario we'd query AMS slots or fallback logic.
	// Here we simply look for the most recently used spool in usage_logs.
	var spoolID int
	row := p.pool.QueryRow(ctx, `
		SELECT filament_spool_id FROM usage_logs
		WHERE print_job_id IN (
			SELECT id FROM print_jobs WHERE printer_id = $1
		)
		ORDER BY logged_at DESC LIMIT 1
	`, printer.ID)
	_ = row.Scan(&spoolID)

	if spoolID == 0 {
		// No prior usage — skip recording (no known spool to deduct from)
		slog.Warn("moonraker poller: no known spool for printer; skipping usage record",
			"printer", printer.Name)
		return nil
	}

	// Compute grams from mm extruded using defaults (1.75mm diameter, PLA density 1.24)
	grams := calculateGrams(stats.FilamentUsedMm, 1.75, 1.24)

	// Create a print job record
	var jobID int
	err := p.pool.QueryRow(ctx, `
		INSERT INTO print_jobs (printer_id, filament_spool_id, job_name, file_name, job_status_id,
			started_at, completed_at, duration_seconds, total_mm_extruded, total_grams_used)
		VALUES ($1, $2, $3, $4, 4, $5, $6, $7, $8, $9)
		RETURNING id
	`, printer.ID, spoolID, stats.Filename, stats.Filename,
		time.Now().Add(-time.Duration(stats.TotalDuration)*time.Second),
		time.Now(),
		int(stats.TotalDuration),
		stats.FilamentUsedMm,
		grams,
	).Scan(&jobID)

	if err != nil {
		return fmt.Errorf("insert print_job failed: %w", err)
	}

	// Create usage_log
	_, err = p.pool.Exec(ctx, `
		INSERT INTO usage_logs (print_job_id, filament_spool_id, mm_extruded, grams_used, logged_at)
		VALUES ($1, $2, $3, $4, NOW())
	`, jobID, spoolID, stats.FilamentUsedMm, grams)

	if err != nil {
		return fmt.Errorf("insert usage_log failed: %w", err)
	}

	slog.Info("moonraker poller: recorded usage",
		"printer", printer.Name,
		"job", stats.Filename,
		"mm", stats.FilamentUsedMm,
		"grams", grams,
	)
	return nil
}

func (p *MoonrakerPoller) broadcastStatus(printerID int, name, status string) {
	if p.sseBC == nil {
		return
	}
	ev, err := sse.NewEvent(sse.EventPrinterStatus, sse.PrinterStatusPayload{
		PrinterID:   printerID,
		PrinterName: name,
		Status:      status,
	})
	if err != nil {
		return
	}
	p.sseBC.Publish(ev)
}

func (p *MoonrakerPoller) broadcastJobStarted(printerID int, jobName string) {
	if p.sseBC == nil {
		return
	}
	ev, err := sse.NewEvent(sse.EventJobStarted, sse.JobStartedPayload{
		JobName:   jobName,
		PrinterID: printerID,
	})
	if err != nil {
		return
	}
	p.sseBC.Publish(ev)
}

func (p *MoonrakerPoller) broadcastJobCompleted(printerID int, jobName string, mmExtruded float64) {
	if p.sseBC == nil {
		return
	}
	grams := calculateGrams(mmExtruded, 1.75, 1.24)
	gramsInt := int(grams)
	ev, err := sse.NewEvent(sse.EventJobCompleted, sse.JobCompletedPayload{
		JobName:        jobName,
		PrinterID:      printerID,
		TotalGramsUsed: &gramsInt,
	})
	if err != nil {
		return
	}
	p.sseBC.Publish(ev)
}

func mapMoonrakerState(state string) string {
	switch state {
	case "printing":
		return "printing"
	case "paused":
		return "paused"
	case "complete", "standby", "cancelled":
		return "idle"
	case "error":
		return "error"
	default:
		return "offline"
	}
}

func isCompleteState(state string) bool {
	return state == "complete" || state == "completed"
}

func calculateGrams(mmExtruded, diameterMm, densityGcm3 float64) float64 {
	if mmExtruded <= 0 {
		return 0
	}
	radiusCm := diameterMm / 2.0 / 10.0
	crossSection := 3.141592653589793 * radiusCm * radiusCm
	volumeCm3 := (mmExtruded / 10.0) * crossSection
	return volumeCm3 * densityGcm3
}

// ---------------------------------------------------------------------------
// Helper for port parsing (Moonraker URL may contain port)
// ---------------------------------------------------------------------------

func extractHostPort(rawURL string) (string, int) {
	// Very simplistic: if rawURL contains ":" after a dot, parse host:port.
	// Otherwise assume host only and return port 80.
	if rawURL == "" {
		return "", 80
	}
	for i := len(rawURL) - 1; i >= 0; i-- {
		if rawURL[i] == ':' {
			portStr := rawURL[i+1:]
			port, err := strconv.Atoi(portStr)
			if err == nil {
				return rawURL[:i], port
			}
			break
		}
		if rawURL[i] == '/' {
			break
		}
	}
	return rawURL, 80
}