import Foundation
import Testing
@testable import DocsKit
#if os(macOS)
import AppKit
#else
import UIKit
#endif

@Test func letterGeometryAndNarrowReflow() {
    let desktop = DocsPageGeometry(viewportWidth: 800, paged: true)
    #expect(desktop.paperWidth == 612)
    #expect(desktop.textWidth == 468)
    #expect(desktop.bodyHeight == 648)
    let phone = DocsPageGeometry(viewportWidth: 320, paged: true)
    #expect(phone.textWidth >= 256)
    let crossing = desktop.lineRect(CGRect(x: 0, y: 710, width: 800, height: 20))
    #expect(crossing.minY == 888)
    let continuous = DocsPageGeometry(viewportWidth: 800, paged: false)
    #expect(continuous.lineRect(CGRect(x: 0, y: 710, width: 800, height: 20)).minY == 710)
}

@MainActor @Test func nativePaginationMovesGlyphsWithoutChangingTextOffsets() {
    let source = String(repeating: "Wrapped text العربية 日本語 🧪 preserves offsets. ", count: 100)
        + "\n" + String(repeating: "Native paging preserves every character and edit offset.\n", count: 100)
    let storage = NSTextStorage(string: source)
    #if os(macOS)
    storage.addAttribute(.font, value: NSFont.systemFont(ofSize: 12), range: NSRange(location: 0, length: storage.length))
    #else
    storage.addAttribute(.font, value: UIFont.systemFont(ofSize: 12), range: NSRange(location: 0, length: storage.length))
    #endif
    let manager = NSLayoutManager()
    let container = DocsPageTextContainer(size: CGSize(width: 800, height: 1_000_000))
    container.lineFragmentPadding = 0
    container.geometry = DocsPageGeometry(viewportWidth: 800, paged: true)
    storage.addLayoutManager(manager)
    manager.addTextContainer(container)
    manager.ensureLayout(for: container)
    var secondPageGlyph: Int?
    manager.enumerateLineFragments(forGlyphRange: NSRange(location: 0, length: manager.numberOfGlyphs)) { rect, _, _, glyphs, _ in
        let page = container.geometry.page(at: rect.minY)
        let top = CGFloat(page) * container.geometry.stride + DocsPageGeometry.verticalMargin
        #expect(rect.minY >= top)
        #expect(rect.maxY <= top + container.geometry.bodyHeight + 0.1)
        #expect(rect.minX >= container.geometry.textX)
        #expect(rect.maxX <= container.geometry.textX + container.geometry.textWidth + 0.1)
        if page > 0 && secondPageGlyph == nil { secondPageGlyph = glyphs.location }
    }
    #expect(secondPageGlyph != nil)
    #expect(storage.string == source)
    let location = manager.characterIndexForGlyph(at: secondPageGlyph ?? 0)
    #expect(location > 0 && location < source.utf16.count)
    storage.replaceCharacters(in: NSRange(location: location, length: 0), with: "🧪")
    #expect((storage.string as NSString).substring(with: NSRange(location: location, length: 2)) == "🧪")
    container.geometry.paged = false
    manager.ensureLayout(for: container)
    #expect(storage.length == source.utf16.count + 2)
}