import test from "node:test";
import assert from "node:assert/strict";
import { mkdtempSync, readdirSync, readFileSync, rmSync, unlinkSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";

const { createResponsesApiTransformStream, createResponsesLogger } =
  await import("../../open-sse/transformer/responsesTransformer.ts");

const encoder = new TextEncoder();
const decoder = new TextDecoder();

async function runTransformStream(chunks, logger = null) {
  const stream = createResponsesApiTransformStream(logger);
  const writer = stream.writable.getWriter();
  const reader = stream.readable.getReader();

  const output = [];
  const readerTask = (async () => {
    while (true) {
      const { value, done } = await reader.read();
      if (done) break;
      output.push(decoder.decode(value));
    }
  })();

  for (const chunk of chunks) {
    await writer.write(encoder.encode(chunk));
  }
  await writer.close();
  await readerTask;

  return output.join("");
}

function parseSseOutput(output) {
  return output
    .trim()
    .split("\n\n")
    .map((entry) => {
      const lines = entry.split("\n");
      const eventLine = lines.find((line) => line.startsWith("event: "));
      const dataLine = lines.find((line) => line.startsWith("data: "));
      return {
        event: eventLine ? eventLine.slice("event: ".length) : null,
        data: dataLine ? dataLine.slice("data: ".length) : null,
      };
    });
}

test("createResponsesApiTransformStream converts plain chat deltas into Responses API events", async () => {
  const output = await runTransformStream([
    'data: {"id":"chatcmpl_1","choices":[{"index":0,"delta":{"content":"Hel"}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{"content":"lo"}}]}\n\n',
    'data: {"usage":{"prompt_tokens":1,"completion_tokens":2,"total_tokens":3}}\n\n',
    'data: {"choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}\n\n',
  ]);

  const events = parseSseOutput(output);
  const types = events.map((event) => event.event || event.data);
  const deltas = events
    .filter((event) => event.event === "response.output_text.delta")
    .map((event) => JSON.parse(event.data));
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;
  const doneMarker = events.at(-1);

  assert.deepEqual(
    deltas.map((delta) => delta.delta),
    ["Hel", "lo"]
  );
  assert.ok(types.includes("response.created"));
  assert.ok(types.includes("response.in_progress"));
  assert.ok(types.includes("response.output_item.added"));
  assert.ok(types.includes("response.output_text.done"));
  assert.equal(completed.output[0].content[0].text, "Hello");
  assert.deepEqual(completed.usage, {
    prompt_tokens: 1,
    completion_tokens: 2,
    total_tokens: 3,
  });
  assert.equal(doneMarker.data, "[DONE]");
});

test("createResponsesApiTransformStream preserves prompt-format think tags by default", async () => {
  const output = await runTransformStream([
    'data: {"id":"chatcmpl_1","model":"gpt-4.1","choices":[{"index":0,"delta":{"content":"<think>plan"}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{"content":"ning</think>answer"}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}\n\n',
  ]);

  const events = parseSseOutput(output);
  const reasoningDeltas = events
    .filter((event) => event.event === "response.reasoning_summary_text.delta")
    .map((event) => JSON.parse(event.data).delta);
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;

  assert.deepEqual(reasoningDeltas, []);
  assert.deepEqual(completed.output[0].content, [
    { type: "output_text", annotations: [], logprobs: [], text: "<think>planning</think>answer" },
  ]);
});

test("createResponsesApiTransformStream extracts think tags for tag-native models", async () => {
  const output = await runTransformStream([
    'data: {"id":"chatcmpl_1","model":"deepseek-ai/DeepSeek-R1","choices":[{"index":0,"delta":{"content":"<think>plan"}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{"content":"ning</think>answer"}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}\n\n',
  ]);

  const events = parseSseOutput(output);
  const reasoningDeltas = events
    .filter((event) => event.event === "response.reasoning_summary_text.delta")
    .map((event) => JSON.parse(event.data).delta);
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;

  assert.deepEqual(reasoningDeltas, ["plan", "ning"]);
  assert.equal(completed.output[0].type, "reasoning");
  assert.deepEqual(completed.output[1].content, [
    { type: "output_text", annotations: [], logprobs: [], text: "answer" },
  ]);
});

test("createResponsesApiTransformStream handles native reasoning content and tool call index replacement", async () => {
  const output = await runTransformStream([
    'data: {"choices":[{"index":0,"delta":{"reasoning_content":"draft "}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_1","function":{"name":"search","arguments":"{\\"q\\":\\"hel"}}]}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_1","function":{"arguments":"lo\\"}"}}]}}]}\n\n',
    'data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_2","function":{"name":"lookup","arguments":"{}"}}]}}]}\n\n',
  ]);

  const events = parseSseOutput(output);
  const addedCalls = events
    .filter((event) => event.event === "response.output_item.added")
    .map((event) => JSON.parse(event.data).item)
    .filter((item) => item.type === "function_call");
  const doneCalls = events
    .filter((event) => event.event === "response.output_item.done")
    .map((event) => JSON.parse(event.data).item)
    .filter((item) => item.type === "function_call");
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;

  assert.deepEqual(
    addedCalls.map((item) => ({ id: item.id, call_id: item.call_id, name: item.name })),
    [
      { id: "fc_call_1", call_id: "call_1", name: "search" },
      { id: "fc_call_2", call_id: "call_2", name: "lookup" },
    ]
  );
  assert.deepEqual(
    doneCalls.map((item) => ({ id: item.id, call_id: item.call_id, name: item.name })),
    [
      { id: "fc_call_1", call_id: "call_1", name: "search" },
      { id: "fc_call_2", call_id: "call_2", name: "lookup" },
    ]
  );
  assert.equal(completed.output[0].type, "reasoning");
  assert.deepEqual(
    completed.output
      .filter((item) => item.type === "function_call")
      .map((item) => ({
        id: item.id,
        call_id: item.call_id,
        name: item.name,
        arguments: item.arguments,
      })),
    [{ id: "fc_call_2", call_id: "call_2", name: "lookup", arguments: "{}" }]
  );
});

test("createResponsesLogger persists input and output event logs on flush", async () => {
  const logsDir = mkdtempSync(join(tmpdir(), "responses-transformer-"));
  const logger = createResponsesLogger("gpt-4o", logsDir);

  assert.ok(logger);

  const output = await runTransformStream(
    ['data: {"choices":[{"index":0,"delta":{"content":"hi"},"finish_reason":"stop"}]}\n\n'],
    logger
  );

  const logRoot = join(logsDir, "logs");
  const [sessionDir] = readdirSync(logRoot);
  const inputLog = readFileSync(join(logRoot, sessionDir, "1_input_stream.txt"), "utf8");
  const outputLog = readFileSync(join(logRoot, sessionDir, "2_output_stream.txt"), "utf8");

  assert.match(sessionDir, /^responses_gpt-4o_/);
  assert.match(inputLog, /"content":"hi"/);
  assert.match(outputLog, /response\.completed/);
  assert.match(output, /data: \[DONE]/);
});

test("createResponsesApiTransformStream ignores malformed events and preserves usage-only chunks", async () => {
  const output = await runTransformStream([
    "event: ping\n\n",
    "data: [DONE]\n\n",
    'data: {"usage":{"prompt_tokens":2,"completion_tokens":1,"total_tokens":3}}\n\n',
    "data: {not-json}\n\n",
    'data: {"id":"chatcmpl_edge","choices":[{"index":0,"delta":{"content":"ok"},"finish_reason":"stop"}]}\n\n',
  ]);

  const events = parseSseOutput(output);
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;

  assert.equal(completed.id, "resp_chatcmpl_edge");
  assert.equal(completed.output[0].content[0].text, "ok");
  assert.deepEqual(completed.usage, {
    prompt_tokens: 2,
    completion_tokens: 1,
    total_tokens: 3,
  });
});

test("createResponsesLogger returns null for invalid base paths and swallows flush write failures", () => {
  const blockedPath = join(tmpdir(), `responses-transformer-blocked-${Date.now()}`);
  writeFileSync(blockedPath, "blocked");

  try {
    const blockedLogger = createResponsesLogger("gpt-4o", blockedPath);
    assert.equal(blockedLogger, null);
  } finally {
    unlinkSync(blockedPath);
  }

  const logsDir = mkdtempSync(join(tmpdir(), "responses-transformer-broken-"));
  const logger = createResponsesLogger("gpt-4o", logsDir);
  const capturedLogs = [];
  const originalConsoleLog = console.log;

  logger.logInput("input");
  logger.logOutput("output");

  const sessionDir = readdirSync(join(logsDir, "logs"))[0];
  rmSync(join(logsDir, "logs", sessionDir), { recursive: true, force: true });
  console.log = (...args) => capturedLogs.push(args.join(" "));

  try {
    logger.flush();
  } finally {
    console.log = originalConsoleLog;
  }

  assert.ok(capturedLogs.some((entry) => entry.includes("[RESPONSES] Failed to write logs:")));
});

test("createResponsesApiTransformStream deduplicates repeated tool argument snapshots", async () => {
  const args = JSON.stringify({ command: "find /tmp -name test.txt" });
  const output = await runTransformStream([
    `data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_1","function":{"name":"shell","arguments":${JSON.stringify(args)}}}]}}]}\n\n`,
    `data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"function":{"arguments":${JSON.stringify(args)}}]},"finish_reason":"tool_calls"}]}\n\n`,
  ]);

  const events = parseSseOutput(output);
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;
  const toolCall = completed.output.find((item) => item.type === "function_call");

  assert.equal(toolCall.arguments, args);
  assert.equal(JSON.parse(toolCall.arguments).command, "find /tmp -name test.txt");

  // The streamed deltas must also reconstruct the arguments exactly once — a
  // duplicated snapshot must not be re-emitted to the client.
  const streamedArgs = events
    .filter((event) => event.event === "response.function_call_arguments.delta")
    .map((event) => JSON.parse(event.data).delta)
    .join("");
  assert.equal(streamedArgs, args);
});

test("createResponsesApiTransformStream concatenates incremental tool argument fragments without dropping repeated chars", async () => {
  // Real providers stream `function.arguments` as small incremental fragments.
  // A doubled char straddling a fragment boundary ("l" + "l -l") must survive
  // — the previous fuzzy-dedup heuristic silently turned `ll -l` into `l -l`.
  const output = await runTransformStream([
    `data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"id":"call_1","function":{"name":"shell","arguments":"{\\"cmd\\":\\"l"}}]}}]}\n\n`,
    `data: {"choices":[{"index":0,"delta":{"tool_calls":[{"index":0,"function":{"arguments":"l -l\\"}"}}]},"finish_reason":"tool_calls"}]}\n\n`,
  ]);

  const events = parseSseOutput(output);
  const completed = JSON.parse(
    events.find((event) => event.event === "response.completed").data
  ).response;
  const toolCall = completed.output.find((item) => item.type === "function_call");

  assert.equal(toolCall.arguments, '{"cmd":"ll -l"}');
  assert.equal(JSON.parse(toolCall.arguments).cmd, "ll -l");

  const streamedArgs = events
    .filter((event) => event.event === "response.function_call_arguments.delta")
    .map((event) => JSON.parse(event.data).delta)
    .join("");
  assert.equal(streamedArgs, '{"cmd":"ll -l"}');
});

test("createResponsesApiTransformStream clears the keepalive timer when the stream is cancelled (no timer leak)", async () => {
  // Regression: the 3s keepalive interval used to be cleared ONLY in flush(), which
  // does not run when the client disconnects mid-stream. The orphaned interval then
  // fired (and threw on the closed controller) forever, leaking one live timer per
  // aborted /v1/responses stream and burning CPU as they accumulated. Verify the timer
  // is cleared when the readable side is cancelled.
  const realSetInterval = globalThis.setInterval;
  const realClearInterval = globalThis.clearInterval;
  const live = new Set();
  globalThis.setInterval = function (handler, timeout, ...args) {
    const id = realSetInterval(handler, timeout, ...args);
    live.add(id);
    return id;
  };
  globalThis.clearInterval = function (id) {
    live.delete(id);
    return realClearInterval(id);
  };

  try {
    const stream = createResponsesApiTransformStream(null, 10);
    const writer = stream.writable.getWriter();
    const reader = stream.readable.getReader();

    // start() runs on construction and creates exactly one keepalive interval.
    assert.equal(live.size, 1, "keepalive interval should be active while streaming");

    await writer.write(
      encoder.encode('data: {"choices":[{"index":0,"delta":{"content":"hi"}}]}\n\n')
    );
    await reader.read();

    // Simulate a client disconnect mid-stream.
    await reader.cancel();

    assert.equal(live.size, 0, "keepalive interval must be cleared when the stream is cancelled");
  } finally {
    globalThis.setInterval = realSetInterval;
    globalThis.clearInterval = realClearInterval;
  }
});

test("createResponsesApiTransformStream keepalive self-clears when enqueue fails on a torn-down controller", async () => {
  // Backstop for transports where neither flush() nor cancel() runs: the keepalive
  // callback must clear its own interval the first time enqueue() throws, instead of
  // re-throwing on every tick forever.
  const realSetInterval = globalThis.setInterval;
  const realClearInterval = globalThis.clearInterval;
  let capturedCallback = null;
  let capturedId = null;
  let cleared = false;
  globalThis.setInterval = function (handler, timeout, ...args) {
    capturedCallback = handler;
    capturedId = realSetInterval(() => {}, 1 << 30, ...args); // inert real timer as the id
    return capturedId;
  };
  globalThis.clearInterval = function (id) {
    if (id === capturedId) cleared = true;
    return realClearInterval(id);
  };

  try {
    const stream = createResponsesApiTransformStream(null, 10);
    // Error the readable side so the controller can no longer accept enqueues.
    await stream.readable.cancel();

    assert.equal(typeof capturedCallback, "function", "keepalive callback should be captured");
    // Manually invoke the keepalive tick: enqueue() will throw on the torn-down
    // controller, and the callback must clear its own interval rather than rethrow.
    assert.doesNotThrow(() => capturedCallback());
    assert.equal(cleared, true, "keepalive interval should self-clear after a failed enqueue");
  } finally {
    globalThis.setInterval = realSetInterval;
    globalThis.clearInterval = realClearInterval;
  }
});