import XCTest
@testable import LChatCore

// The format-as-you-type brain (ComposerRules.swift) — semantics pinned here,
// and the regex literals drift-gated against web/static/composer-pm.js (the
// ComposerTypeaheadTests pattern): a web-side rule change fails this suite
// until the native mirror follows.
final class ComposerRulesTests: XCTestCase {
    private var repoRoot: URL {
        URL(fileURLWithPath: #filePath)
            .deletingLastPathComponent() // Tests/LChatCoreTests
            .deletingLastPathComponent() // Tests
            .deletingLastPathComponent() // LChatCore
            .deletingLastPathComponent() // ios
            .deletingLastPathComponent() // repo
    }

    // MARK: inline completions

    func testMarkCompletions() {
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "**bold**"),
                       InlineCompletion(replaceRange: 0..<8, content: "bold", mark: .bold))
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "say *it*"),
                       InlineCompletion(replaceRange: 4..<8, content: "it", mark: .italic))
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "`code`"),
                       InlineCompletion(replaceRange: 0..<6, content: "code", mark: .code))
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "~gone~"),
                       InlineCompletion(replaceRange: 0..<6, content: "gone", mark: .strike))
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "say _it_"),
                       InlineCompletion(replaceRange: 4..<8, content: "it", mark: .italic))
    }

    func testUnderscoreNeverFiresIntraword() {
        XCTAssertNil(inlineCompletion(lineUpToCaret: "snake_case_"))
        XCTAssertNil(inlineCompletion(lineUpToCaret: "a_b_"))
    }

    func testStrongWinsBeforeEm() {
        // "**bold**" must fire strong, and the half-typed "**bold*" must not
        // half-fire the em rule (its lookbehind rejects the second star).
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "**bold**")?.mark, .bold)
        XCTAssertNil(inlineCompletion(lineUpToCaret: "**bold*"))
    }

    func testTildeLookbehind() {
        XCTAssertNil(inlineCompletion(lineUpToCaret: "~~s~"), "double-tilde opener never pairs with a single closer")
    }

    func testNoFireOnWhitespaceEdges() {
        XCTAssertNil(inlineCompletion(lineUpToCaret: "** x**"))
        XCTAssertNil(inlineCompletion(lineUpToCaret: "*x *"))
    }

    func testUnicodeContentAndOffsets() {
        // replaceRange is UTF-16: ✨ is BMP (1 unit), 😀 is a surrogate pair (2).
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "✨ **bí**"),
                       InlineCompletion(replaceRange: 2..<8, content: "bí", mark: .bold))
        XCTAssertEqual(inlineCompletion(lineUpToCaret: "😀 **x**"),
                       InlineCompletion(replaceRange: 3..<8, content: "x", mark: .bold))
    }

    // MARK: drift gate against the web rules

    func testRegexLiteralsMatchComposerPmJs() throws {
        let js = try String(contentsOf: repoRoot.appendingPathComponent("web/static/composer-pm.js"), encoding: .utf8)
        // The exact JS regex literals the Swift patterns transliterate. If a
        // rule changes on the web, its literal disappears and this fails.
        let literals = [
            #"/\*\*([^*\s](?:[^*]*[^*\s])?)\*\*$/"#,
            #"/(?<!\*)\*([^*\s](?:[^*]*[^*\s])?)\*$/"#,
            #"/(?<![\w_])_([^_\s](?:[^_]*[^_\s])?)_$/"#,
            #"/`([^`\s](?:[^`]*[^`\s])?)`$/"#,
            #"/(?<!~)~([^~\s](?:[^~]*[^~\s])?)~$/"#,
        ]
        for literal in literals {
            XCTAssertTrue(js.contains(literal), "composer-pm.js no longer contains \(literal) — mirror the rule change into ComposerRules.swift")
        }
    }
}