import SwiftUI
import UIKit
import CoreText

/// The web UI's design tokens (`internal/web/static/style.css` in
/// krz/gitbay), so the two surfaces read as one product. Every pair is
/// the stylesheet's light/dark value for the same variable.
extension Color {

    nonisolated private static func paired(_ light: UInt32, _ dark: UInt32) -> Color {
        Color(UIColor { traits in
            UIColor(hex: traits.userInterfaceStyle == .dark ? dark : light)
        })
    }

    /// --accent: links and focus.
    nonisolated static let gbAccent = paired(0x0000F0, 0x6272FF)
    /// --ok: open things, passing builds, verified signatures.
    nonisolated static let gbOK = paired(0x0A7D3C, 0x3FCE7A)
    /// --bad: closed without merging, failures, bad signatures.
    nonisolated static let gbBad = paired(0xC62828, 0xFF6B6B)
    /// --done: merged.
    nonisolated static let gbDone = paired(0x6B21A8, 0xC084FC)
    /// --warn: text-sized warnings.
    nonisolated static let gbWarn = paired(0xC2410C, 0xFF6B3D)
    /// --mark: the brand orange, bars and underlines.
    nonisolated static let gbMark = paired(0xE4572E, 0xFF6B3D)
    /// --diff-add / --diff-del: row grounds in diffs.
    nonisolated static let gbDiffAdd = paired(0xE4F6EA, 0x0D2A18)
    nonisolated static let gbDiffDel = paired(0xFDEAEA, 0x2C1113)
    /// --code-bg: code blocks.
    nonisolated static let gbCodeBackground = paired(0xF5F5F5, 0x050505)
    /// --fill-subtle: hunk headers and quiet fills.
    nonisolated static let gbFillSubtle = paired(0xECECEC, 0x161616)
    /// --faint: hairlines, row separators, and an empty calendar cell.
    nonisolated static let gbFaint = paired(0xEAEAEA, 0x1C1C1C)
    /// --bg: the page ground the accent is mixed toward. Chrome uses the
    /// system background; this is for blends that must match the web.
    nonisolated static let gbBackground = paired(0xFFFFFF, 0x0A0A0A)
    /// --line: control borders and table edges.
    nonisolated static let gbLine = paired(0xD4D4D4, 0x2E2E2E)
}

extension UIColor {
    nonisolated convenience init(hex: UInt32) {
        self.init(
            red: CGFloat((hex >> 16) & 0xFF) / 255,
            green: CGFloat((hex >> 8) & 0xFF) / 255,
            blue: CGFloat(hex & 0xFF) / 255,
            alpha: 1
        )
    }
}

/// The web's chip shape: --r-pill is 2px, not a capsule.
nonisolated let gbChipShape = RoundedRectangle(cornerRadius: 2)

/// Atkinson Hyperlegible, the faces the web serves, scaled with Dynamic
/// Type. Falls back to the system face wherever the fonts fail to
/// register.
extension Font {

    nonisolated static func gbSans(_ style: TextStyle) -> Font {
        .custom("Atkinson Hyperlegible Next", size: gbSize(style), relativeTo: style)
    }

    nonisolated static func gbMono(_ style: TextStyle) -> Font {
        .custom("Atkinson Hyperlegible Mono", size: gbSize(style), relativeTo: style)
    }

    /// Base sizes tracking the system text styles.
    nonisolated private static func gbSize(_ style: TextStyle) -> CGFloat {
        switch style {
        case .largeTitle: 34
        case .title: 28
        case .title2: 22
        case .title3: 20
        case .headline: 17
        case .body: 17
        case .callout: 16
        case .subheadline: 15
        case .footnote: 13
        case .caption: 12
        case .caption2: 11
        @unknown default: 17
        }
    }
}

/// Registers the bundled faces once at launch. Registration failure is
/// survivable: Font.custom falls back to the system face.
enum GitbayFonts {
    static func register() {
        let names = [
            "AtkinsonNext-Regular", "AtkinsonNext-Bold", "AtkinsonNext-Semibold",
            "AtkinsonNext-Italic", "AtkinsonMono-Regular", "AtkinsonMono-Semibold",
        ]
        let urls = names.compactMap {
            Bundle.main.url(forResource: $0, withExtension: "ttf")
        }
        guard !urls.isEmpty else { return }
        CTFontManagerRegisterFontURLs(urls as CFArray, .process, true, nil)
    }
}

/// The web's notice idiom: a 3px stripe in the state's color down the
/// left edge, not a tinted fill. `.error` uses --bad, `.notice` --ok;
/// anything the server refused is --warn.
struct GBNotice: View {
    let text: String
    let color: Color

    init(_ text: String, _ color: Color = .gbBad) {
        self.text = text
        self.color = color
    }

    var body: some View {
        HStack(alignment: .top, spacing: 10) {
            Rectangle()
                .fill(color)
                .frame(width: 3)
            Text(text)
                .font(.gbSans(.subheadline))
                .frame(maxWidth: .infinity, alignment: .leading)
        }
        .fixedSize(horizontal: false, vertical: true)
        .padding(.vertical, 2)
    }
}

/// The web's `.chip` recipe: state color, a 7% tint ground, a 35% tint
/// border, 2px radius.
struct GBChip: View {
    let text: String
    let color: Color

    init(_ text: String, _ color: Color) {
        self.text = text
        self.color = color
    }

    var body: some View {
        Text(text)
            .font(.gbSans(.caption2).weight(.medium))
            .foregroundStyle(color)
            .padding(.horizontal, 7)
            .padding(.vertical, 1)
            .background(color.opacity(0.07), in: gbChipShape)
            .overlay(gbChipShape.stroke(color.opacity(0.35), lineWidth: 1))
    }
}