import XCTest
@testable import LChatCore

// 🤖 The perf ledger's pure halves: JSONL parsing (lenient — a torn line from
// a crash mid-append must never sink the export), the Settings summary line
// (pluralisation is a shipping requirement), and the export's diagnostic
// byte cap.
final class PerfTests: XCTestCase {
    func testEventRoundtripAndLenientParse() throws {
        let event = PerfEvent(t: 1_753_000_000_000, kind: "slow", name: "feed.openThread",
                              ms: 1812.5, detail: "214 messages")
        let line = String(data: try JSONEncoder().encode(event), encoding: .utf8)!
        let jsonl = line + "\n{\"torn\":tru\n" + line + "\nnot json at all\n"
        let parsed = PerfEvent.parse(jsonl: jsonl)
        XCTAssertEqual(parsed, [event, event])
    }

    func testSummaryEmpty() {
        XCTAssertNil(PerfEvent.summary([]))
        // Boot/metric/note events alone aren't "cuts" — nothing to say.
        XCTAssertNil(PerfEvent.summary([PerfEvent(t: 0, kind: "boot", name: "boot.firstFrame", ms: 500)]))
    }

    func testSummarySingularAndPlural() {
        let oneEach = [
            PerfEvent(t: 0, kind: "hang", name: "main.hang", ms: 900),
            PerfEvent(t: 1, kind: "slow", name: "api.get", ms: 1500),
        ]
        XCTAssertEqual(PerfEvent.summary(oneEach), "1 hang · 1 slow moment · worst api.get 1.5s")

        let several = [
            PerfEvent(t: 0, kind: "hang", name: "main.hang", ms: 900),
            PerfEvent(t: 1, kind: "hang", name: "main.hang", ms: 450),
            PerfEvent(t: 2, kind: "slow", name: "api.get", ms: 1500),
            PerfEvent(t: 3, kind: "slow", name: "feed.openThread", ms: 2400),
        ]
        XCTAssertEqual(PerfEvent.summary(several), "2 hangs · 2 slow moments · worst feed.openThread 2.4s")
    }

    func testSummaryHangsOnly() {
        let hangs = [PerfEvent(t: 0, kind: "hang", name: "main.hang", ms: 600)]
        XCTAssertEqual(PerfEvent.summary(hangs), "1 hang")
    }

    func testSummaryIncludesHitches() {
        let one = [PerfEvent(t: 0, kind: "hitch", name: "frame.hitch", ms: 180)]
        XCTAssertEqual(PerfEvent.summary(one), "1 hitch")
        let mixed = [
            PerfEvent(t: 0, kind: "hang", name: "main.hang", ms: 600),
            PerfEvent(t: 1, kind: "hitch", name: "frame.hitch", ms: 180),
            PerfEvent(t: 2, kind: "hitch", name: "frame.hitch", ms: 250),
        ]
        XCTAssertEqual(PerfEvent.summary(mixed), "1 hang · 2 hitches")
    }

    func testCapDiagnosticsKeepsNewestUnderBudget() {
        let a = String(repeating: "a", count: 100)
        let b = String(repeating: "b", count: 100)
        let c = String(repeating: "c", count: 100)
        // Newest first in, newest kept: the cap stops at the first payload
        // that would overflow, never skipping ahead to a smaller older one.
        XCTAssertEqual(PerfExport.capDiagnostics([a, b, c], maxBytes: 250), [a, b])
        XCTAssertEqual(PerfExport.capDiagnostics([a, b, c], maxBytes: 1000), [a, b, c])
        XCTAssertEqual(PerfExport.capDiagnostics([a], maxBytes: 50), [])
        XCTAssertEqual(PerfExport.capDiagnostics([], maxBytes: 1000), [])
    }
}