import Foundation
import UIKit
import CoreImage
import CoreImage.CIFilterBuiltins
import WidgetKit

// ──────────────────────────────────────────────────────────────────────
// WidgetBridge.swift
// TARGET: Main app only (NOT the widget extension).
//
// Responsibilities:
//   1. Pre-blurs album art for the widget background (CIGaussianBlur)
//   2. Pushes playback state to App Group on every change
//   3. Observes Darwin notifications for widget → app commands
//   4. Reloads widget timelines when state changes
//
// Integration: call WidgetBridge.shared.start() once from app launch,
// then call updateNowPlaying(...) from AudioPlayer on every state change.
// ──────────────────────────────────────────────────────────────────────

final class WidgetBridge {

    static let shared = WidgetBridge()

    private let state = WidgetSharedState.shared
    private let blurContext = CIContext(options: [.useSoftwareRenderer: false])
    private var isObserving = false

    /// Cached blurred art to avoid re-blurring on every time-observer tick.
    /// Reset when the cover art ID changes.
    private var cachedBlurCoverArtId: String?
    private var cachedBlurData: Data?
    private var cachedArtData: Data?
    private var cachedAccentHex: String?
    private var cachedSecondaryHex: String?

    private init() {}

    // MARK: - Lifecycle

    /// Call once from app launch (e.g. NavidromePlayerApp.init or AppDelegate).
    /// Sets up the Darwin notification observer for widget commands.
    func start() {
        guard !isObserving else { return }
        isObserving = true

        let center = CFNotificationCenterGetDarwinNotifyCenter()
        let observer = Unmanaged.passUnretained(self).toOpaque()

        CFNotificationCenterAddObserver(
            center,
            observer,
            { _, observer, _, _, _ in
                guard let observer else { return }
                let bridge = Unmanaged<WidgetBridge>.fromOpaque(observer).takeUnretainedValue()
                DispatchQueue.main.async { bridge.handleWidgetCommand() }
            },
            kWidgetCommandNotification,
            nil,
            .deliverImmediately
        )
    }

    // MARK: - Push State to Widget

    /// Full state push — call on song change, play/pause, queue edit.
    /// Blurs the album art if the cover changed; skips blur if same art.
    func updateNowPlaying(
        title: String,
        artist: String,
        album: String,
        isPlaying: Bool,
        currentTime: TimeInterval,
        duration: TimeInterval,
        coverArtId: String?,
        coverArtImage: UIImage?,
        queue: [(title: String, artist: String, coverData: Data?)],
        waveformSamples: [Float]? = nil,
        crossfadeAt: TimeInterval? = nil
    ) {
        // Only re-process if the cover art actually changed
        if let id = coverArtId, id != cachedBlurCoverArtId, let image = coverArtImage {
            cachedBlurCoverArtId = id
            cachedArtData = image.jpegData(compressionQuality: 0.7)
            let blurred = blurImage(image, radius: 60)
            cachedBlurData = blurred?.jpegData(compressionQuality: 0.5)

            // Extract dominant color for adaptive theming
            let (accent, secondary) = extractColors(from: image)
            cachedAccentHex = accent
            cachedSecondaryHex = secondary
        }

        let queueItems = queue.prefix(3).map {
            WidgetQueueItem(title: $0.title, artist: $0.artist, coverArtData: $0.coverData)
        }

        state.pushState(
            title: title,
            artist: artist,
            album: album,
            isPlaying: isPlaying,
            currentTime: currentTime,
            duration: duration,
            coverArtJPEG: cachedArtData,
            blurredArtJPEG: cachedBlurData,
            queueNext: queueItems,
            waveformSamples: waveformSamples,
            accentColorHex: cachedAccentHex,
            secondaryColorHex: cachedSecondaryHex,
            crossfadeAt: crossfadeAt
        )

        WidgetCenter.shared.reloadAllTimelines()
    }

    /// Lightweight position-only push — call from the time observer (~every 5s).
    /// Does NOT reload timelines (the timeline entries already project forward).
    func updatePosition(currentTime: TimeInterval, isPlaying: Bool) {
        state.pushPosition(currentTime: currentTime, isPlaying: isPlaying)
    }

    /// Clear widget state (e.g. on logout or server change).
    func clear() {
        cachedBlurCoverArtId = nil
        cachedBlurData = nil
        cachedArtData = nil
        cachedAccentHex = nil
        cachedSecondaryHex = nil
        state.clearAll()
        WidgetCenter.shared.reloadAllTimelines()
    }

    // MARK: - Handle Widget Commands

    /// Called by the Darwin notification observer when the app process is running.
    private func handleWidgetCommand() {
        processAnyPendingCommand()
    }

    /// Check App Group UserDefaults for any pending widget command and execute it.
    /// Called from two places:
    ///   1. Darwin notification observer (app is running in background with audio)
    ///   2. resumeVisTimers / foreground entry (app was suspended, Darwin missed)
    func processAnyPendingCommand() {
        guard let cmd = state.dequeueCommand() else { return }
        let player = AudioPlayer.shared

        switch cmd {
        case .play:
            // Idempotency: don't resume if already playing (avoids audio glitches)
            guard !player.isPlaying else { break }
            // If no song is loaded (app was killed), restore from saved state first
            if player.currentSong == nil {
                if let saved = PlaybackStateStore.shared.load() {
                    player.play(song: saved.currentSong, fromQueue: saved.queue, at: saved.index)
                }
            } else {
                player.resume()
            }

        case .pause:
            // Idempotency: don't pause if already paused
            guard player.isPlaying else { break }
            player.pause()

        case .next:
            player.next()

        case .previous:
            player.previous()

        case .seekForward15:
            guard player.duration > 0 else { break }
            player.seek(to: min(player.currentTime + 15, player.duration))

        case .seekBackward15:
            player.seek(to: max(player.currentTime - 15, 0))

        case .seekTo:
            guard player.duration > 0 else { break }
            let target = state.seekToTime
            player.seek(to: min(max(target, 0), player.duration))
        }

        DebugLogger.shared.log("Widget command: \(cmd.rawValue)", category: "Widget")
    }

    // MARK: - Color Extraction

    /// Extract dominant color from cover art using CIAreaAverage, then compute
    /// a secondary color for text/accents. Returns (accentHex, secondaryHex).
    private func extractColors(from image: UIImage) -> (String, String) {
        let accentHex = dominantColorHex(from: image)
        let secondaryHex = computeSecondaryHex(from: accentHex)
        return (accentHex, secondaryHex)
    }

    /// Uses CIAreaAverage to find the single dominant color in the image.
    /// Returns a hex string like "E74C3C".
    private func dominantColorHex(from image: UIImage) -> String {
        guard let cgImage = image.cgImage else { return "E74C3C" }
        let ciImage = CIImage(cgImage: cgImage)

        let extent = ciImage.extent
        guard let filter = CIFilter(name: "CIAreaAverage",
                                    parameters: [kCIInputImageKey: ciImage,
                                                 kCIInputExtentKey: CIVector(cgRect: extent)]),
              let output = filter.outputImage else { return "E74C3C" }

        // Read the single 1×1 pixel result
        var pixel = [UInt8](repeating: 0, count: 4)
        blurContext.render(output,
                          toBitmap: &pixel,
                          rowBytes: 4,
                          bounds: CGRect(x: 0, y: 0, width: 1, height: 1),
                          format: .RGBA8,
                          colorSpace: CGColorSpaceCreateDeviceRGB())

        var r = CGFloat(pixel[0]) / 255.0
        var g = CGFloat(pixel[1]) / 255.0
        var b = CGFloat(pixel[2]) / 255.0

        // Boost saturation — averaged colors tend to be muddy.
        // Convert to HSB, clamp brightness, increase saturation.
        var h: CGFloat = 0, s: CGFloat = 0, br: CGFloat = 0, a: CGFloat = 0
        UIColor(red: r, green: g, blue: b, alpha: 1).getHue(&h, saturation: &s, brightness: &br, alpha: &a)

        // Ensure usable contrast: not too dark, not too light
        br = max(0.35, min(0.80, br))
        s  = max(0.30, min(0.90, s * 1.3))

        let boosted = UIColor(hue: h, saturation: s, brightness: br, alpha: 1)
        boosted.getRed(&r, green: &g, blue: &b, alpha: &a)

        let ri = Int(r * 255), gi = Int(g * 255), bi = Int(b * 255)
        return String(format: "%02X%02X%02X", ri, gi, bi)
    }

    /// Compute a lighter/desaturated secondary color from the accent hex.
    /// Used for artist text, time labels, and glass tint.
    private func computeSecondaryHex(from hex: String) -> String {
        let (r, g, b) = hexToRGB(hex)
        var h: CGFloat = 0, s: CGFloat = 0, br: CGFloat = 0, a: CGFloat = 0
        UIColor(red: r, green: g, blue: b, alpha: 1).getHue(&h, saturation: &s, brightness: &br, alpha: &a)

        // Lighter, less saturated version for text
        let secondary = UIColor(hue: h, saturation: s * 0.5, brightness: min(br + 0.25, 0.95), alpha: 1)
        var sr: CGFloat = 0, sg: CGFloat = 0, sb: CGFloat = 0
        secondary.getRed(&sr, green: &sg, blue: &sb, alpha: &a)

        return String(format: "%02X%02X%02X", Int(sr * 255), Int(sg * 255), Int(sb * 255))
    }

    private func hexToRGB(_ hex: String) -> (CGFloat, CGFloat, CGFloat) {
        var h = hex
        if h.hasPrefix("#") { h = String(h.dropFirst()) }
        guard h.count == 6, let val = UInt64(h, radix: 16) else {
            return (0.9, 0.3, 0.24) // fallback pink
        }
        return (CGFloat((val >> 16) & 0xFF) / 255.0,
                CGFloat((val >> 8)  & 0xFF) / 255.0,
                CGFloat( val        & 0xFF) / 255.0)
    }

    // MARK: - Gaussian Blur

    /// Applies a heavy gaussian blur to the image for the widget background.
    /// Uses CoreImage on the GPU — fast even for large images.
    private func blurImage(_ image: UIImage, radius: CGFloat) -> UIImage? {
        // Downscale to ~200px wide first — no need for full-res blur
        let maxDim: CGFloat = 200
        let scale = min(maxDim / image.size.width, maxDim / image.size.height, 1.0)
        let targetSize = CGSize(
            width: image.size.width * scale,
            height: image.size.height * scale
        )

        UIGraphicsBeginImageContextWithOptions(targetSize, true, 1.0)
        image.draw(in: CGRect(origin: .zero, size: targetSize))
        let downscaled = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        guard let cgImage = (downscaled ?? image).cgImage else { return nil }
        let ciImage = CIImage(cgImage: cgImage)

        // Clamp edges to prevent dark border artifacts from the blur kernel
        let clamped = ciImage.clampedToExtent()

        guard let blurFilter = CIFilter(name: "CIGaussianBlur") else { return nil }
        blurFilter.setValue(clamped, forKey: kCIInputImageKey)
        blurFilter.setValue(radius, forKey: kCIInputRadiusKey)

        guard let output = blurFilter.outputImage else { return nil }

        // Crop back to original extent (blur expands the image)
        let cropped = output.cropped(to: ciImage.extent)

        guard let cgResult = blurContext.createCGImage(cropped, from: ciImage.extent) else { return nil }
        return UIImage(cgImage: cgResult)
    }
}