import { describe, expect, it } from "@suaveplan/testing/runner";
import { CHUNKS_CODES } from "../error-codes.js";
import { encodeChunk, parseChunk, validateChunk } from "./chunk.js";

describe("CHUNKS-FORMAT-V1-01 — Chunk binary layout is byte-exact", () => {
    it("round-trips every field at exact offsets", { timeout: 5000 }, () => {
        const metadata = {
            version: 0x0001,
            fileId: new Uint8Array(32).fill(0xab),
            chunkId: 7,
            totalChunks: 10,
            fileSize: 12345n,
            chunkSize: 65536,
            payloadLen: 100,
            flags: 0x0000,
            nonce: new Uint8Array(24).fill(0xcd),
            aeadTag: new Uint8Array(16).fill(0xef),
        };
        const sig = new Uint8Array(64).fill(0x12);
        const ciphertext = new Uint8Array(100).fill(0x34);

        const encoded = encodeChunk({ metadata, sig, ciphertext });
        expect(encoded.length).toBe(164 + 100);

        const view = new DataView(encoded.buffer, encoded.byteOffset);
        expect(view.getUint16(0, false)).toBe(0x0001);
        expect(encoded.slice(2, 34)).toEqual(metadata.fileId);
        expect(view.getUint32(34, false)).toBe(7);
        expect(view.getUint32(38, false)).toBe(10);
        expect(view.getBigUint64(42, false)).toBe(12345n);
        expect(view.getUint32(50, false)).toBe(65536);
        expect(view.getUint32(54, false)).toBe(100);
        expect(view.getUint16(58, false)).toBe(0x0000);
        expect(encoded.slice(60, 84)).toEqual(metadata.nonce);
        expect(encoded.slice(84, 100)).toEqual(metadata.aeadTag);
        expect(encoded.slice(100, 164)).toEqual(sig);
        expect(encoded.slice(164)).toEqual(ciphertext);

        const parsed = parseChunk(encoded);
        expect(parsed.metadata.version).toBe(0x0001);
        expect(parsed.metadata.chunkId).toBe(7);
        expect(parsed.metadata.payloadLen).toBe(100);
        expect(parsed.sig).toEqual(sig);
        expect(parsed.ciphertext).toEqual(ciphertext);
    });
});

describe("CHUNKS-FORMAT-V1-02 — flags reserved in v1", () => {
    it("rejects non-zero flags", { timeout: 5000 }, () => {
        const metadata = {
            version: 0x0001,
            fileId: new Uint8Array(32),
            chunkId: 0,
            totalChunks: 1,
            fileSize: 1n,
            chunkSize: 65536,
            payloadLen: 1,
            flags: 0x0001,
            nonce: new Uint8Array(24),
            aeadTag: new Uint8Array(16),
        };
        const chunk = {
            metadata,
            sig: new Uint8Array(64),
            ciphertext: new Uint8Array(1),
        };
        expect(() => validateChunk(chunk)).toThrow();
        try {
            validateChunk(chunk);
        } catch (e) {
            expect((e as Error).code).toBe(CHUNKS_CODES.FLAGS_RESERVED_NONZERO);
        }
    });
});

describe("CHUNKS-FORMAT-V1-03 — Payload length invariants", () => {
    it("rejects non-final chunk payloadLen mismatch", { timeout: 5000 }, () => {
        const metadata = {
            version: 0x0001,
            fileId: new Uint8Array(32),
            chunkId: 0,
            totalChunks: 2,
            fileSize: 100000n,
            chunkSize: 65536,
            payloadLen: 100,
            flags: 0x0000,
            nonce: new Uint8Array(24),
            aeadTag: new Uint8Array(16),
        };
        const chunk = {
            metadata,
            sig: new Uint8Array(64),
            ciphertext: new Uint8Array(100),
        };
        expect(() => validateChunk(chunk)).toThrow();
        try {
            validateChunk(chunk);
        } catch (e) {
            expect((e as Error).code).toBe(CHUNKS_CODES.PAYLOAD_LEN_INVALID);
        }
    });

    it("accepts correct non-final payloadLen", { timeout: 5000 }, () => {
        const metadata = {
            version: 0x0001,
            fileId: new Uint8Array(32),
            chunkId: 0,
            totalChunks: 2,
            fileSize: 100000n,
            chunkSize: 65536,
            payloadLen: 65536 - 164,
            flags: 0x0000,
            nonce: new Uint8Array(24),
            aeadTag: new Uint8Array(16),
        };
        const chunk = {
            metadata,
            sig: new Uint8Array(64),
            ciphertext: new Uint8Array(65536 - 164),
        };
        expect(() => validateChunk(chunk)).not.toThrow();
    });

    it("rejects final chunk payloadLen mismatch", { timeout: 5000 }, () => {
        const metadata = {
            version: 0x0001,
            fileId: new Uint8Array(32),
            chunkId: 1,
            totalChunks: 2,
            fileSize: 500n,
            chunkSize: 65536,
            payloadLen: 100,
            flags: 0x0000,
            nonce: new Uint8Array(24),
            aeadTag: new Uint8Array(16),
        };
        const chunk = {
            metadata,
            sig: new Uint8Array(64),
            ciphertext: new Uint8Array(100),
        };
        expect(() => validateChunk(chunk)).toThrow();
        try {
            validateChunk(chunk);
        } catch (e) {
            expect((e as Error).code).toBe(CHUNKS_CODES.PAYLOAD_LEN_INVALID);
        }
    });
});

describe("CHUNKS-FORMAT-V1-04 — parseChunk edge cases", () => {
    it("rejects chunk shorter than header", { timeout: 5000 }, () => {
        expect(() => parseChunk(new Uint8Array(10))).toThrow();
        try {
            parseChunk(new Uint8Array(10));
        } catch (e) {
            expect((e as Error).code).toBe(CHUNKS_CODES.METADATA_INVALID);
        }
    });

    it("rejects unsupported chunk version", { timeout: 5000 }, () => {
        const metadata = {
            version: 0x0002,
            fileId: new Uint8Array(32),
            chunkId: 0,
            totalChunks: 1,
            fileSize: 1n,
            chunkSize: 65536,
            payloadLen: 1,
            flags: 0x0000,
            nonce: new Uint8Array(24),
            aeadTag: new Uint8Array(16),
        };
        const chunk = {
            metadata,
            sig: new Uint8Array(64),
            ciphertext: new Uint8Array(1),
        };
        expect(() => validateChunk(chunk)).toThrow();
        try {
            validateChunk(chunk);
        } catch (e) {
            expect((e as Error).code).toBe(CHUNKS_CODES.VERSION_UNSUPPORTED);
        }
    });
});