import XCTest
@testable import SaplingEditor

final class DocumentLineIndexTests: XCTestCase {
    func testLFLineBoundaries() {
        assertLineIndex(
            source: "One\nTwo\nThree",
            expectedSources: ["One", "Two", "Three"],
            expectedRanges: [
                NSRange(location: 0, length: 3),
                NSRange(location: 4, length: 3),
                NSRange(location: 8, length: 5)
            ],
            expectedEndings: [.lf, .lf, .none]
        )
    }

    func testCRLFLineBoundaries() {
        assertLineIndex(
            source: "One\r\nTwo\r\nThree",
            expectedSources: ["One", "Two", "Three"],
            expectedRanges: [
                NSRange(location: 0, length: 3),
                NSRange(location: 5, length: 3),
                NSRange(location: 10, length: 5)
            ],
            expectedEndings: [.crlf, .crlf, .none]
        )
    }

    func testCRLineBoundaries() {
        assertLineIndex(
            source: "One\rTwo\rThree",
            expectedSources: ["One", "Two", "Three"],
            expectedRanges: [
                NSRange(location: 0, length: 3),
                NSRange(location: 4, length: 3),
                NSRange(location: 8, length: 5)
            ],
            expectedEndings: [.cr, .cr, .none]
        )
    }

    func testMixedLineBoundaries() {
        assertLineIndex(
            source: "One\nTwo\r\nThree\rFour",
            expectedSources: ["One", "Two", "Three", "Four"],
            expectedRanges: [
                NSRange(location: 0, length: 3),
                NSRange(location: 4, length: 3),
                NSRange(location: 9, length: 5),
                NSRange(location: 15, length: 4)
            ],
            expectedEndings: [.lf, .crlf, .cr, .none]
        )
    }

    func testTrailingBlankLineForEveryLineEnding() {
        XCTAssertEqual(DocumentLineIndex(source: "One\n").boundaries.map(\.contentRange.location), [0, 4])
        XCTAssertEqual(DocumentLineIndex(source: "One\r\n").boundaries.map(\.contentRange.location), [0, 5])
        XCTAssertEqual(DocumentLineIndex(source: "One\r").boundaries.map(\.contentRange.location), [0, 4])
    }

    func testActiveLineDetectionAcrossCRLFBoundaries() {
        let source = "One\r\nTwo\r\nThree"

        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 0, in: source), 0)
        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 3, in: source), 0)
        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 4, in: source), 0)
        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 5, in: source), 1)
        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 8, in: source), 1)
        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 9, in: source), 1)
        XCTAssertEqual(EditorActiveLineTracker.lineIndex(containing: 10, in: source), 2)
    }

    func testEditorLinesPreserveCRLFSourceRangesAndModes() {
        let lines = EditorActiveLineTracker.lines(from: "One\r\nTwo\r\nThree", activeLineIndex: 1)

        XCTAssertEqual(lines.count, 3)
        XCTAssertEqual(lines.map(\.source), ["One", "Two", "Three"])
        XCTAssertEqual(lines.map(\.range), [
            NSRange(location: 0, length: 3),
            NSRange(location: 5, length: 3),
            NSRange(location: 10, length: 5)
        ])
        XCTAssertEqual(lines.map(\.mode), [.rendered, .source, .rendered])
    }

    func testOffsetAndLineMappingUsesCachedBoundaries() {
        let source = "One\nTwo\r\nThree\rFour"
        let index = DocumentLineIndex(source: source)

        XCTAssertEqual(index.lineCount, 4)
        XCTAssertEqual(index.lineStartOffset(forLine: 0), 0)
        XCTAssertEqual(index.lineStartOffset(forLine: 1), 4)
        XCTAssertEqual(index.lineStartOffset(forLine: 2), 9)
        XCTAssertEqual(index.lineStartOffset(forLine: 3), 15)
        XCTAssertEqual(index.lineIndex(containing: 0), 0)
        XCTAssertEqual(index.lineIndex(containing: 4), 1)
        XCTAssertEqual(index.lineIndex(containing: 14), 2)
        XCTAssertEqual(index.lineIndex(containing: 15), 3)
    }

    func testIncrementalInsertionWithoutNewlineMatchesFullRebuild() {
        assertIncrementalEdit(
            source: "One\nTwo\nThree",
            range: NSRange(location: 5, length: 0),
            replacement: " updated"
        )
    }

    func testIncrementalInsertionWithLFMatchesFullRebuild() {
        assertIncrementalEdit(
            source: "One\nTwo\nThree",
            range: NSRange(location: 7, length: 0),
            replacement: "\nInserted"
        )
    }

    func testIncrementalInsertionWithCRLFMatchesFullRebuild() {
        assertIncrementalEdit(
            source: "One\r\nTwo\r\nThree",
            range: NSRange(location: 8, length: 0),
            replacement: "\r\nInserted"
        )
    }

    func testIncrementalDeletionAcrossLinesMatchesFullRebuild() {
        assertIncrementalEdit(
            source: "One\nTwo\nThree\nFour",
            range: NSRange(location: 2, length: 10),
            replacement: ""
        )
    }

    func testIncrementalReplacementAcrossMixedLineEndingsMatchesFullRebuild() {
        assertIncrementalEdit(
            source: "One\nTwo\r\nThree\rFour",
            range: NSRange(location: 3, length: 11),
            replacement: "\r\nReplacement\n"
        )
    }

    func testIncrementalEditAtCRLFBoundaryMatchesFullRebuild() {
        assertIncrementalEdit(
            source: "One\r\nTwo\r\nThree",
            range: NSRange(location: 3, length: 2),
            replacement: "\n"
        )
    }

    func testIncrementalLargeDocumentEditMatchesFullRebuild() {
        let source = (0..<10_000)
            .map { "Line \($0)\r\n" }
            .joined()

        assertIncrementalEdit(
            source: source,
            range: NSRange(location: 42_000, length: 5),
            replacement: "changed\nwith\nnew lines"
        )
    }

    func testBenchmarkDocumentSegmentsIntoPhysicalLines() throws {
        let url = URL(fileURLWithPath: "/Users/feror/Sapling/Docs/Benchmarks/5mb.md")
        let source = try String(contentsOf: url, encoding: .utf8)
        let lines = EditorActiveLineTracker.lines(from: source, activeLineIndex: 0)

        XCTAssertEqual(lines.count, 51_482)
        XCTAssertEqual(lines[0].source, "# ExampleFile.com - Example Files")
        XCTAssertEqual(lines[1].source, "")
        XCTAssertEqual(lines[2].source, "- ✨ExampleFile ✨")
        XCTAssertEqual(lines.filter { $0.mode == .source }.count, 1)
        XCTAssertEqual(lines.filter { $0.mode == .rendered }.count, 51_481)
    }

    private func assertLineIndex(
        source: String,
        expectedSources: [String],
        expectedRanges: [NSRange],
        expectedEndings: [LineEndingStrategy],
        file: StaticString = #filePath,
        line: UInt = #line
    ) {
        let index = DocumentLineIndex(source: source)
        let lines = index.editorLines(activeLineIndex: 0)

        XCTAssertEqual(lines.map(\.source), expectedSources, file: file, line: line)
        XCTAssertEqual(index.boundaries.map(\.contentRange), expectedRanges, file: file, line: line)
        XCTAssertEqual(index.boundaries.map(\.lineEnding), expectedEndings, file: file, line: line)
    }

    private func assertIncrementalEdit(
        source: String,
        range: NSRange,
        replacement: String,
        file: StaticString = #filePath,
        line: UInt = #line
    ) {
        var incremental = DocumentLineIndex(source: source)
        incremental.replaceCharacters(in: range, with: replacement)

        let rebuiltSource = (source as NSString).replacingCharacters(in: range, with: replacement)
        let rebuilt = DocumentLineIndex(source: rebuiltSource)

        XCTAssertEqual(incremental.source, rebuiltSource, file: file, line: line)
        XCTAssertEqual(incremental.boundaries, rebuilt.boundaries, file: file, line: line)
        XCTAssertEqual(
            incremental.editorLines(activeLineIndex: 0).map(\.source),
            rebuilt.editorLines(activeLineIndex: 0).map(\.source),
            file: file,
            line: line
        )
    }
}