import CoreText
import Foundation
#if os(macOS)
import AppKit
typealias DocsPlatformFont = NSFont
#else
import UIKit
typealias DocsPlatformFont = UIFont
#endif

@MainActor enum DocsFonts {
    private static let registered: Void = {
        for family in ["Sans", "Serif", "Mono"] {
            for face in ["Regular", "Bold", "Italic", "BoldItalic"] {
                let name = "Liberation\(family)-\(face)"
                if let url = DocsResources.bundle.url(forResource: name, withExtension: "ttf") {
                    CTFontManagerRegisterFontsForURL(url as CFURL, .process, nil)
                }
            }
        }
    }()
    static func font(marks: [String: JSONValue], size baseSize: CGFloat, heading: Bool) -> DocsPlatformFont {
        _ = registered
        var size = baseSize
        for key in marks.keys.sorted() where key.hasPrefix("size_") {
            if let value = Double(key.dropFirst(5)), [8, 9, 10, 11, 12, 14, 18, 24, 36, 48, 72].contains(value) { size = value }
            else if key == "size_sm" { size = 10 }
            else if key == "size_lg" { size = 14 }
            else if key == "size_xl" { size = 18 }
        }
        if marks["code"] != nil { size *= 0.85 }
        let family = marks["font_mono"] != nil || marks["code"] != nil ? "Mono" : marks["font_serif"] != nil ? "Serif" : "Sans"
        let bold = marks["strong"] != nil || heading
        let italic = marks["em"] != nil
        let face = bold ? (italic ? "BoldItalic" : "Bold") : (italic ? "Italic" : "Regular")
        let postScriptName = "Liberation\(family)" + (face == "Regular" ? "" : "-\(face)")
        return DocsPlatformFont(name: postScriptName, size: size) ?? DocsPlatformFont.systemFont(ofSize: size)
    }
}