//
//  LoadingView.swift
//  App for Indeed
//

import Cocoa
import QuartzCore

final class LoadingView: NSView {
    private enum Theme {
        static let brandBlue = NSColor(srgbRed: 37 / 255, green: 87 / 255, blue: 167 / 255, alpha: 1)
        static let brandBlueLight = NSColor(srgbRed: 54 / 255, green: 110 / 255, blue: 198 / 255, alpha: 1)
        static let pageBackgroundTop = NSColor(srgbRed: 252 / 255, green: 253 / 255, blue: 255 / 255, alpha: 1)
        static let pageBackgroundBottom = NSColor(srgbRed: 241 / 255, green: 245 / 255, blue: 252 / 255, alpha: 1)
        static let iconWell = NSColor(srgbRed: 239 / 255, green: 246 / 255, blue: 255 / 255, alpha: 1)
        static let headingBlue = NSColor(srgbRed: 0, green: 82 / 255, blue: 204 / 255, alpha: 1)
        static let subtitleText = NSColor(srgbRed: 51 / 255, green: 65 / 255, blue: 85 / 255, alpha: 1)
        static let statusText = NSColor(srgbRed: 118 / 255, green: 118 / 255, blue: 118 / 255, alpha: 1)
        static let waveTint = NSColor(srgbRed: 186 / 255, green: 210 / 255, blue: 253 / 255, alpha: 1)
        static let badgeFill = NSColor(srgbRed: 37 / 255, green: 87 / 255, blue: 167 / 255, alpha: 0.1)
        static let badgeText = NSColor(srgbRed: 37 / 255, green: 87 / 255, blue: 167 / 255, alpha: 1)
    }

    private let backgroundGradientHost = NSView()
    private let heroBackground = LoadingSplashBackgroundView()
    private let iconWell = NSView()
    private let iconView = NSImageView()
    private let aiBadgeHost = NSView()
    private let aiBadgeLabel = NSTextField(labelWithString: "AI-POWERED")
    private let titleLabel = NSTextField(labelWithString: AppMarketingLinks.displayName)
    private let subtitleLabel = NSTextField(labelWithString: "Find your perfect job with the power of AI.")
    private let statusLabel = NSTextField(labelWithString: "Starting up…")
    private let progressBar = LoadingProgressBarView()
    private let thinkingIndicator = ChatThinkingIndicatorView(
        compact: false,
        accessibilityLabel: "Loading \(AppMarketingLinks.displayName)"
    )

    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        setUp()
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layout() {
        super.layout()
        backgroundGradientHost.layer?.sublayers?
            .filter { $0.name == "pageGradient" }
            .forEach { $0.frame = backgroundGradientHost.bounds }
        progressBar.layoutProgressFill(animated: false)
    }

    override func viewDidMoveToWindow() {
        super.viewDidMoveToWindow()
        if window != nil {
            startAnimating()
        } else {
            stopAnimating()
        }
    }

    func setStatus(_ message: String, progress: CGFloat) {
        statusLabel.stringValue = message
        progressBar.setProgress(progress, animated: true)
        setAccessibilityLabel("Loading \(AppMarketingLinks.displayName). \(message)")
    }

    func startAnimating() {
        thinkingIndicator.startAnimatingIfNeeded()
        progressBar.startShimmerIfNeeded()
        heroBackground.startAmbientAnimationIfNeeded()
    }

    func stopAnimating() {
        thinkingIndicator.stopAnimating()
        progressBar.stopShimmer()
        heroBackground.stopAmbientAnimation()
    }

    private func setUp() {
        wantsLayer = true

        backgroundGradientHost.translatesAutoresizingMaskIntoConstraints = false
        backgroundGradientHost.wantsLayer = true

        heroBackground.translatesAutoresizingMaskIntoConstraints = false
        heroBackground.waveTint = Theme.waveTint

        iconWell.translatesAutoresizingMaskIntoConstraints = false
        iconWell.wantsLayer = true
        iconWell.layer?.backgroundColor = Theme.iconWell.cgColor
        iconWell.layer?.cornerRadius = 28
        if #available(macOS 11.0, *) {
            iconWell.layer?.cornerCurve = .continuous
        }
        iconWell.layer?.masksToBounds = true
        iconWell.layer?.borderColor = NSColor.white.cgColor
        iconWell.layer?.borderWidth = 3
        iconWell.layer?.shadowColor = NSColor.black.cgColor
        iconWell.layer?.shadowOpacity = 0.08
        iconWell.layer?.shadowRadius = 16
        iconWell.layer?.shadowOffset = CGSize(width: 0, height: -4)

        iconView.translatesAutoresizingMaskIntoConstraints = false
        iconView.imageScaling = .scaleProportionallyUpOrDown
        iconView.image = NSApp.applicationIconImage

        aiBadgeHost.translatesAutoresizingMaskIntoConstraints = false
        aiBadgeHost.wantsLayer = true
        aiBadgeHost.layer?.backgroundColor = Theme.badgeFill.cgColor
        aiBadgeHost.layer?.cornerRadius = 10
        if #available(macOS 11.0, *) {
            aiBadgeHost.layer?.cornerCurve = .continuous
        }

        aiBadgeLabel.translatesAutoresizingMaskIntoConstraints = false
        aiBadgeLabel.font = .systemFont(ofSize: 11, weight: .bold)
        aiBadgeLabel.textColor = Theme.badgeText
        aiBadgeLabel.alignment = .center
        aiBadgeLabel.isEditable = false
        aiBadgeLabel.isSelectable = false
        aiBadgeLabel.isBezeled = false
        aiBadgeLabel.drawsBackground = false

        titleLabel.translatesAutoresizingMaskIntoConstraints = false
        titleLabel.font = .systemFont(ofSize: 44, weight: .bold)
        titleLabel.textColor = Theme.headingBlue
        titleLabel.alignment = .center

        subtitleLabel.translatesAutoresizingMaskIntoConstraints = false
        subtitleLabel.font = .systemFont(ofSize: 18, weight: .regular)
        subtitleLabel.textColor = Theme.subtitleText
        subtitleLabel.alignment = .center
        subtitleLabel.maximumNumberOfLines = 2
        subtitleLabel.lineBreakMode = .byWordWrapping

        statusLabel.translatesAutoresizingMaskIntoConstraints = false
        statusLabel.font = .systemFont(ofSize: 15, weight: .medium)
        statusLabel.textColor = Theme.statusText
        statusLabel.alignment = .center
        statusLabel.maximumNumberOfLines = 2
        statusLabel.lineBreakMode = .byTruncatingTail

        progressBar.translatesAutoresizingMaskIntoConstraints = false

        thinkingIndicator.translatesAutoresizingMaskIntoConstraints = false

        iconWell.addSubview(iconView)
        aiBadgeHost.addSubview(aiBadgeLabel)

        let heroStack = NSStackView(views: [
            iconWell,
            aiBadgeHost,
            titleLabel,
            subtitleLabel,
            statusLabel,
            thinkingIndicator,
            progressBar
        ])
        heroStack.orientation = .vertical
        heroStack.alignment = .centerX
        heroStack.spacing = 18
        heroStack.setCustomSpacing(28, after: iconWell)
        heroStack.setCustomSpacing(12, after: aiBadgeHost)
        heroStack.setCustomSpacing(10, after: titleLabel)
        heroStack.setCustomSpacing(28, after: subtitleLabel)
        heroStack.setCustomSpacing(24, after: statusLabel)
        heroStack.setCustomSpacing(24, after: thinkingIndicator)
        heroStack.translatesAutoresizingMaskIntoConstraints = false

        addSubview(backgroundGradientHost)
        addSubview(heroBackground)
        addSubview(heroStack)

        NSLayoutConstraint.activate([
            backgroundGradientHost.leadingAnchor.constraint(equalTo: leadingAnchor),
            backgroundGradientHost.trailingAnchor.constraint(equalTo: trailingAnchor),
            backgroundGradientHost.topAnchor.constraint(equalTo: topAnchor),
            backgroundGradientHost.bottomAnchor.constraint(equalTo: bottomAnchor),

            heroBackground.leadingAnchor.constraint(equalTo: leadingAnchor),
            heroBackground.trailingAnchor.constraint(equalTo: trailingAnchor),
            heroBackground.topAnchor.constraint(equalTo: topAnchor),
            heroBackground.bottomAnchor.constraint(equalTo: bottomAnchor),

            iconWell.widthAnchor.constraint(equalToConstant: 128),
            iconWell.heightAnchor.constraint(equalToConstant: 128),

            iconView.centerXAnchor.constraint(equalTo: iconWell.centerXAnchor),
            iconView.centerYAnchor.constraint(equalTo: iconWell.centerYAnchor),
            iconView.widthAnchor.constraint(equalToConstant: 88),
            iconView.heightAnchor.constraint(equalToConstant: 88),

            aiBadgeHost.heightAnchor.constraint(equalToConstant: 26),
            aiBadgeLabel.leadingAnchor.constraint(equalTo: aiBadgeHost.leadingAnchor, constant: 14),
            aiBadgeLabel.trailingAnchor.constraint(equalTo: aiBadgeHost.trailingAnchor, constant: -14),
            aiBadgeLabel.centerYAnchor.constraint(equalTo: aiBadgeHost.centerYAnchor),

            heroStack.centerXAnchor.constraint(equalTo: centerXAnchor),
            heroStack.centerYAnchor.constraint(equalTo: centerYAnchor),
            heroStack.leadingAnchor.constraint(greaterThanOrEqualTo: leadingAnchor, constant: 48),
            heroStack.trailingAnchor.constraint(lessThanOrEqualTo: trailingAnchor, constant: -48),
            heroStack.widthAnchor.constraint(lessThanOrEqualToConstant: 720),

            subtitleLabel.widthAnchor.constraint(lessThanOrEqualTo: heroStack.widthAnchor),
            statusLabel.widthAnchor.constraint(lessThanOrEqualTo: heroStack.widthAnchor),

            progressBar.widthAnchor.constraint(equalTo: heroStack.widthAnchor, multiplier: 0.78),
            progressBar.widthAnchor.constraint(lessThanOrEqualToConstant: 560),
            progressBar.widthAnchor.constraint(greaterThanOrEqualToConstant: 280)
        ])

        installPageGradient()
        setAccessibilityElement(true)
        setAccessibilityRole(.group)
        setAccessibilityLabel("Loading \(AppMarketingLinks.displayName)")
    }

    private func installPageGradient() {
        let gradient = CAGradientLayer()
        gradient.name = "pageGradient"
        gradient.colors = [
            Theme.pageBackgroundTop.cgColor,
            Theme.pageBackgroundBottom.cgColor
        ]
        gradient.startPoint = CGPoint(x: 0.5, y: 1)
        gradient.endPoint = CGPoint(x: 0.5, y: 0)
        gradient.frame = backgroundGradientHost.bounds
        backgroundGradientHost.layer?.addSublayer(gradient)
    }

}

// MARK: - Loading progress bar

private final class LoadingProgressBarView: NSView {
    private enum Theme {
        static let brandBlue = NSColor(srgbRed: 37 / 255, green: 87 / 255, blue: 167 / 255, alpha: 1)
        static let brandBlueLight = NSColor(srgbRed: 54 / 255, green: 110 / 255, blue: 198 / 255, alpha: 1)
        static let trackFill = NSColor(srgbRed: 228 / 255, green: 233 / 255, blue: 242 / 255, alpha: 1)
        static let trackBorder = NSColor(srgbRed: 212 / 255, green: 218 / 255, blue: 230 / 255, alpha: 1)
        static let percentText = NSColor(srgbRed: 37 / 255, green: 87 / 255, blue: 167 / 255, alpha: 1)
    }

    private let track = NSView()
    private let fill = NSView()
    private let percentLabel = NSTextField(labelWithString: "0%")
    private var fillWidthConstraint: NSLayoutConstraint?
    private var fillGradientLayer: CAGradientLayer?
    private var shimmerLayer: CAGradientLayer?
    private var targetProgress: CGFloat = 0.04

    override var intrinsicContentSize: NSSize {
        NSSize(width: 420, height: 44)
    }

    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        setUp()
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layout() {
        super.layout()
        layoutProgressFill(animated: false)
    }

    func setProgress(_ progress: CGFloat, animated: Bool) {
        targetProgress = min(max(progress, 0), 1)
        let percent = Int((targetProgress * 100).rounded())
        percentLabel.stringValue = "\(percent)%"
        layoutProgressFill(animated: animated)
    }

    func layoutProgressFill(animated: Bool) {
        layoutSubtreeIfNeeded()
        let trackWidth = track.bounds.width
        guard trackWidth > 1 else { return }
        let width = max(trackWidth * max(targetProgress, 0.03), 12)
        fillWidthConstraint?.constant = width

        guard animated else {
            fillGradientLayer?.frame = fill.bounds
            shimmerLayer?.frame = fill.bounds
            return
        }
        NSAnimationContext.runAnimationGroup { context in
            context.duration = 0.45
            context.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
            context.allowsImplicitAnimation = true
            fill.animator().layoutSubtreeIfNeeded()
        } completionHandler: { [weak self] in
            guard let self else { return }
            self.fillGradientLayer?.frame = self.fill.bounds
            self.shimmerLayer?.frame = self.fill.bounds
        }
    }

    func startShimmerIfNeeded() {
        guard !NSWorkspace.shared.accessibilityDisplayShouldReduceMotion,
              let shimmerLayer else { return }
        shimmerLayer.removeAnimation(forKey: "shimmer")
        let move = CABasicAnimation(keyPath: "transform.translation.x")
        move.fromValue = -fill.bounds.width * 0.6
        move.toValue = fill.bounds.width * 0.6
        move.duration = 1.35
        move.repeatCount = .greatestFiniteMagnitude
        move.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        shimmerLayer.add(move, forKey: "shimmer")
    }

    func stopShimmer() {
        shimmerLayer?.removeAnimation(forKey: "shimmer")
    }

    private func setUp() {
        translatesAutoresizingMaskIntoConstraints = false

        track.translatesAutoresizingMaskIntoConstraints = false
        track.wantsLayer = true
        track.layer?.backgroundColor = Theme.trackFill.cgColor
        track.layer?.borderColor = Theme.trackBorder.cgColor
        track.layer?.borderWidth = 1
        track.layer?.cornerRadius = 7
        if #available(macOS 11.0, *) {
            track.layer?.cornerCurve = .continuous
        }
        track.layer?.masksToBounds = true
        track.setContentHuggingPriority(.defaultLow, for: .horizontal)
        track.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)

        fill.translatesAutoresizingMaskIntoConstraints = false
        fill.wantsLayer = true
        fill.layer?.cornerRadius = 7
        if #available(macOS 11.0, *) {
            fill.layer?.cornerCurve = .continuous
        }
        fill.layer?.masksToBounds = true

        let fillGradient = CAGradientLayer()
        fillGradient.colors = [
            Theme.brandBlueLight.cgColor,
            Theme.brandBlue.cgColor
        ]
        fillGradient.startPoint = CGPoint(x: 0, y: 0.5)
        fillGradient.endPoint = CGPoint(x: 1, y: 0.5)
        fillGradient.cornerRadius = 7
        fill.layer?.addSublayer(fillGradient)
        fillGradientLayer = fillGradient

        let shimmer = CAGradientLayer()
        shimmer.colors = [
            NSColor.white.withAlphaComponent(0).cgColor,
            NSColor.white.withAlphaComponent(0.45).cgColor,
            NSColor.white.withAlphaComponent(0).cgColor
        ]
        shimmer.startPoint = CGPoint(x: 0, y: 0.5)
        shimmer.endPoint = CGPoint(x: 1, y: 0.5)
        shimmer.locations = [0, 0.5, 1]
        fill.layer?.addSublayer(shimmer)
        shimmerLayer = shimmer

        percentLabel.translatesAutoresizingMaskIntoConstraints = false
        percentLabel.font = .monospacedDigitSystemFont(ofSize: 13, weight: .semibold)
        percentLabel.textColor = Theme.percentText
        percentLabel.alignment = .right
        percentLabel.setContentHuggingPriority(.required, for: .horizontal)

        track.addSubview(fill)

        let row = NSStackView(views: [track, percentLabel])
        row.orientation = .horizontal
        row.spacing = 14
        row.alignment = .centerY
        row.translatesAutoresizingMaskIntoConstraints = false
        addSubview(row)

        fillWidthConstraint = fill.widthAnchor.constraint(equalToConstant: 12)
        fillWidthConstraint?.isActive = true

        NSLayoutConstraint.activate([
            row.leadingAnchor.constraint(equalTo: leadingAnchor),
            row.trailingAnchor.constraint(equalTo: trailingAnchor),
            row.topAnchor.constraint(equalTo: topAnchor),
            row.bottomAnchor.constraint(equalTo: bottomAnchor),

            track.heightAnchor.constraint(equalToConstant: 14),

            fill.leadingAnchor.constraint(equalTo: track.leadingAnchor),
            fill.topAnchor.constraint(equalTo: track.topAnchor),
            fill.bottomAnchor.constraint(equalTo: track.bottomAnchor),

            percentLabel.widthAnchor.constraint(equalToConstant: 44)
        ])

        setAccessibilityElement(true)
        setAccessibilityRole(.progressIndicator)
        setAccessibilityLabel("Loading progress")
    }
}

// MARK: - Full-page decorative background (matches dashboard welcome hero)

private final class LoadingSplashBackgroundView: NSView {
    var waveTint = NSColor(srgbRed: 186 / 255, green: 210 / 255, blue: 253 / 255, alpha: 1)

    override var isFlipped: Bool { true }

    override func draw(_ dirtyRect: NSRect) {
        NSColor.clear.setFill()
        bounds.fill()
        guard bounds.width > 24, bounds.height > 24 else { return }
        drawSideWaves(in: bounds, isLeft: true)
        drawSideWaves(in: bounds, isLeft: false)
        drawAmbientSparkles(in: bounds)
    }

    func startAmbientAnimationIfNeeded() {
        guard !NSWorkspace.shared.accessibilityDisplayShouldReduceMotion else { return }
        let anim = CABasicAnimation(keyPath: "opacity")
        anim.fromValue = 0.92
        anim.toValue = 1
        anim.duration = 2.4
        anim.autoreverses = true
        anim.repeatCount = .greatestFiniteMagnitude
        layer?.add(anim, forKey: "ambientPulse")
    }

    func stopAmbientAnimation() {
        layer?.removeAnimation(forKey: "ambientPulse")
    }

    private func drawSideWaves(in bounds: NSRect, isLeft: Bool) {
        for i in 0..<12 {
            let path = NSBezierPath()
            path.lineWidth = 1.2
            path.lineCapStyle = .round
            let phase = CGFloat(i) * 0.88
            let base = CGFloat(i + 1) * 14 + 8
            var first = true
            for y in stride(from: CGFloat(0), through: bounds.height, by: 2.4) {
                let wobble = sin(y * 0.042 + phase) * (5 + CGFloat(i % 5))
                let x = isLeft ? (base + wobble) : (bounds.width - base - wobble)
                let point = NSPoint(x: x, y: y)
                if first {
                    path.move(to: point)
                    first = false
                } else {
                    path.line(to: point)
                }
            }
            let fade = 1 - CGFloat(i) / 13
            waveTint.withAlphaComponent((0.1 + CGFloat(i % 3) * 0.024) * fade).setStroke()
            path.stroke()
        }
    }

    private func drawAmbientSparkles(in bounds: NSRect) {
        let accent = NSColor(srgbRed: 0, green: 82 / 255, blue: 204 / 255, alpha: 1)
        let specs: [(CGFloat, CGFloat, CGFloat, CGFloat)] = [
            (0.06, 0.1, 12, 0.32),
            (0.94, 0.08, 14, 0.36),
            (0.12, 0.38, 7, 0.22),
            (0.88, 0.36, 8, 0.24),
            (0.5, 0.05, 10, 0.18),
            (0.22, 0.72, 6, 0.16),
            (0.78, 0.68, 9, 0.2),
            (0.04, 0.55, 5, 0.14),
            (0.96, 0.52, 6, 0.15)
        ]
        for (nx, ny, size, a) in specs {
            let center = NSPoint(x: bounds.width * nx, y: bounds.height * ny)
            fillFourPointStar(center: center, radius: size, color: accent.withAlphaComponent(a))
        }
    }

    private func fillFourPointStar(center: NSPoint, radius: CGFloat, color: NSColor) {
        let path = NSBezierPath()
        for i in 0..<4 {
            let angle = CGFloat(i) * .pi / 2 - .pi / 2
            let point = NSPoint(
                x: center.x + cos(angle) * radius,
                y: center.y + sin(angle) * radius
            )
            if i == 0 {
                path.move(to: point)
            } else {
                path.line(to: point)
            }
        }
        path.close()
        color.setFill()
        path.fill()
    }
}