import AppKit
import SwiftUI

enum ProviderIconAsset {
    static func name(for provider: ProviderID) -> String {
        switch provider {
        case .cursor: "ProviderCursor"
        case .claude: "ProviderClaude"
        }
    }
}

enum MenuBarIconRenderer {
    /// MenuBarExtra ignores SwiftUI layout and NSImage.size — rasterize to exact points.
    static func sizedImage(for provider: ProviderID, height: CGFloat = MenuBarMetrics.iconHeight) -> NSImage {
        let source = loadProviderImage(for: provider)
        guard let source else {
            return NSImage(size: NSSize(width: height, height: height))
        }

        var sourceSize = source.size
        if sourceSize.width <= 0 || sourceSize.height <= 0 {
            sourceSize = NSSize(width: 24, height: 24)
        }

        let aspect = sourceSize.width / sourceSize.height
        let pointSize = NSSize(width: height * aspect, height: height)
        let scale = NSScreen.main?.backingScaleFactor ?? 2
        let pixelWidth = max(Int((pointSize.width * scale).rounded(.up)), 1)
        let pixelHeight = max(Int((pointSize.height * scale).rounded(.up)), 1)

        guard let rep = NSBitmapImageRep(
            bitmapDataPlanes: nil,
            pixelsWide: pixelWidth,
            pixelsHigh: pixelHeight,
            bitsPerSample: 8,
            samplesPerPixel: 4,
            hasAlpha: true,
            isPlanar: false,
            colorSpaceName: .deviceRGB,
            bytesPerRow: 0,
            bitsPerPixel: 0
        ) else {
            return NSImage(size: pointSize)
        }
        rep.size = pointSize

        NSGraphicsContext.saveGraphicsState()
        if let context = NSGraphicsContext(bitmapImageRep: rep) {
            NSGraphicsContext.current = context
            context.imageInterpolation = .high

            let dest = NSRect(origin: .zero, size: pointSize)
            let src = NSRect(origin: .zero, size: sourceSize)

            source.draw(
                in: dest,
                from: src,
                operation: .sourceOver,
                fraction: 1.0,
                respectFlipped: false,
                hints: [.interpolation: NSImageInterpolation.high]
            )
        }
        NSGraphicsContext.restoreGraphicsState()

        let image = NSImage(size: pointSize)
        image.addRepresentation(rep)
        image.isTemplate = true
        return image
    }

    private static func loadProviderImage(for provider: ProviderID) -> NSImage? {
        var image: NSImage?
        NSApp.effectiveAppearance.performAsCurrentDrawingAppearance {
            image = NSImage(named: ProviderIconAsset.name(for: provider))
        }
        return image
    }
}

/// Settings and other in-app UI — keep full size.
struct ProviderBrandIcon: View {
    let provider: ProviderID
    var size: CGFloat = 18

    var body: some View {
        Image(ProviderIconAsset.name(for: provider))
            .resizable()
            .interpolation(.high)
            .antialiased(true)
            .aspectRatio(contentMode: .fit)
            .frame(width: size, height: size)
    }
}

enum MenuBarMetrics {
    static let iconHeight: CGFloat = 18
    static let textSize: CGFloat = 11
    static let providerSpacing: CGFloat = 8
    static let itemSpacing: CGFloat = 4
    static let labelHeight: CGFloat = 20
}

struct ProviderMenuBarIconView: View {
    let providerID: ProviderID
    let state: ProviderDisplayState?
    let settings: AppSettings

    @Environment(\.colorScheme) private var colorScheme

    private var selectedMetrics: [UsageMetric] {
        settings.settings(for: providerID).menuBarMetrics
    }

    private var badgeText: String? {
        guard let snapshot = state?.snapshot else { return nil }
        return snapshot.menuBarDisplay(for: selectedMetrics)
    }

    /// Always show icon + text — this app has no Dock icon.
    private var statusText: String {
        if state?.isLoading == true { return "…" }
        if let badgeText { return badgeText }
        if state?.errorMessage != nil { return "!" }
        return "—"
    }

    var body: some View {
        HStack(spacing: MenuBarMetrics.itemSpacing) {
            Image(nsImage: MenuBarIconRenderer.sizedImage(for: providerID))
                .renderingMode(.template)
                .foregroundStyle(.primary)
                .frame(width: MenuBarMetrics.iconHeight, height: MenuBarMetrics.iconHeight)
                .opacity(state?.errorMessage != nil ? 0.45 : 1.0)

            Text(statusText)
                .font(.system(size: MenuBarMetrics.textSize, weight: .medium))
                .foregroundStyle(state?.errorMessage != nil ? .red : .primary)
                .lineLimit(1)
        }
        .fixedSize(horizontal: true, vertical: false)
        .frame(height: MenuBarMetrics.labelHeight)
        .id(colorScheme)
        .help(helpText)
    }

    private var helpText: String {
        if let error = state?.errorMessage {
            return "\(providerID.displayName): \(error)"
        }
        if statusText != "—", statusText != "…" {
            return "\(providerID.displayName): \(statusText)"
        }
        return providerID.displayName
    }
}