import type { Message } from "@langchain/langgraph-sdk";
import { describe, expect, test } from "vitest";

import {
  extractContentFromMessage,
  extractReasoningContentFromMessage,
  getAssistantTurnCopyData,
  getAssistantTurnUsageMessages,
  getMessageGroups,
  getStreamingMessageLookup,
  hasContent,
  hasReasoning,
  isAssistantMessageGroupStreaming,
} from "@/core/messages/utils";

function aiMessage(content: string): Message {
  return {
    id: "ai-1",
    type: "ai",
    content,
  } as Message;
}

test("aggregates token usage messages once per assistant turn", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Plan a trip",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "",
      tool_calls: [{ id: "tool-1", name: "web_search", args: {} }],
      usage_metadata: { input_tokens: 10, output_tokens: 5, total_tokens: 15 },
    },
    {
      id: "tool-1-result",
      type: "tool",
      name: "web_search",
      tool_call_id: "tool-1",
      content: "[]",
    },
    {
      id: "ai-2",
      type: "ai",
      content: "Here is the itinerary",
      usage_metadata: { input_tokens: 2, output_tokens: 8, total_tokens: 10 },
    },
    {
      id: "human-2",
      type: "human",
      content: "Make it shorter",
    },
    {
      id: "ai-3",
      type: "ai",
      content: "Short version",
      usage_metadata: { input_tokens: 1, output_tokens: 1, total_tokens: 2 },
    },
  ] as Message[];

  const groups = getMessageGroups(messages);
  const usageMessagesByGroupIndex = getAssistantTurnUsageMessages(groups);

  expect(groups.map((group) => group.type)).toEqual([
    "human",
    "assistant:processing",
    "assistant",
    "human",
    "assistant",
  ]);

  expect(
    usageMessagesByGroupIndex.map(
      (groupMessages) => groupMessages?.map((message) => message.id) ?? null,
    ),
  ).toEqual([null, null, ["ai-1", "ai-2"], null, ["ai-3"]]);
});

describe("inline <think> tag splitting", () => {
  test("strips a fully closed <think> block from AI content", () => {
    const message = aiMessage("<think>internal reasoning</think>final answer");
    expect(extractContentFromMessage(message)).toBe("final answer");
    expect(extractReasoningContentFromMessage(message)).toBe(
      "internal reasoning",
    );
  });

  test("strips multiple closed <think> blocks and joins their reasoning", () => {
    const message = aiMessage(
      "<think>step one</think>between<think>step two</think>after",
    );
    expect(extractContentFromMessage(message)).toBe("betweenafter");
    expect(extractReasoningContentFromMessage(message)).toBe(
      "step one\n\nstep two",
    );
  });

  test("during streaming, an unclosed <think> tag does not leak its tail into content", () => {
    // Simulates accumulated content mid-stream, before </think> arrives.
    const message = aiMessage(
      "<think>I need to analyze the user's question step by",
    );
    expect(extractContentFromMessage(message)).toBe("");
    expect(extractContentFromMessage(message)).not.toContain("<think>");
    expect(extractReasoningContentFromMessage(message)).toBe(
      "I need to analyze the user's question step by",
    );
  });

  test("preamble before an unclosed <think> stays in content", () => {
    const message = aiMessage(
      "Here is part of the answer.<think>but wait, let me reconsider",
    );
    expect(extractContentFromMessage(message)).toBe(
      "Here is part of the answer.",
    );
    expect(extractReasoningContentFromMessage(message)).toBe(
      "but wait, let me reconsider",
    );
  });

  test("closed <think> followed by a trailing unclosed <think> merges both into reasoning", () => {
    const message = aiMessage(
      "<think>first step</think>partial answer<think>second step still streaming",
    );
    expect(extractContentFromMessage(message)).toBe("partial answer");
    expect(extractReasoningContentFromMessage(message)).toBe(
      "first step\n\nsecond step still streaming",
    );
  });

  test("hasReasoning recognises an unclosed <think> tag mid-stream", () => {
    expect(hasReasoning(aiMessage("<think>thinking in progress"))).toBe(true);
  });

  test("hasContent excludes an unclosed <think> tail when no preamble exists", () => {
    expect(hasContent(aiMessage("<think>thinking in progress"))).toBe(false);
  });

  test("hasContent stays true when preamble precedes an unclosed <think>", () => {
    expect(hasContent(aiMessage("preamble<think>still thinking"))).toBe(true);
  });

  test("a lone <think> open tag with no body yields no reasoning and no content", () => {
    const message = aiMessage("<think>");
    expect(extractContentFromMessage(message)).toBe("");
    expect(extractReasoningContentFromMessage(message)).toBeNull();
    expect(hasReasoning(message)).toBe(false);
  });

  test("a literal <think> inside markdown inline code is not treated as reasoning", () => {
    const message = aiMessage(
      "Use `<think>` markers to delimit reasoning sections.",
    );
    expect(extractContentFromMessage(message)).toBe(
      "Use `<think>` markers to delimit reasoning sections.",
    );
    expect(extractReasoningContentFromMessage(message)).toBeNull();
    expect(hasReasoning(message)).toBe(false);
  });

  test("a backtick-prefixed <think> mid-stream is not split into reasoning", () => {
    // Simulates the moment the model has emitted the opening backtick and
    // `<think>` for a literal documentation reference, before the closing
    // backtick arrives. The pre-fix behaviour would have permanently
    // truncated the content here.
    const message = aiMessage("Documentation: `<think>");
    expect(extractContentFromMessage(message)).toBe("Documentation: `<think>");
    expect(extractReasoningContentFromMessage(message)).toBeNull();
  });
});

test("hides internal todo reminder messages from message groups", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Audit the middleware",
    },
    {
      id: "todo-reminder-1",
      type: "human",
      name: "todo_completion_reminder",
      content: "<system_reminder>finish todos</system_reminder>",
    },
    {
      id: "todo-reminder-2",
      type: "human",
      name: "todo_reminder",
      content: "<system_reminder>remember todos</system_reminder>",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Done",
    },
  ] as Message[];

  const groups = getMessageGroups(messages);

  expect(groups.map((group) => group.type)).toEqual(["human", "assistant"]);
  expect(
    groups.flatMap((group) => group.messages).map((message) => message.id),
  ).toEqual(["human-1", "ai-1"]);
});

test("hides assistant copy data while that turn is streaming", () => {
  const messages = [
    {
      id: "ai-1",
      type: "ai",
      content: "Partial answer",
    },
  ] as Message[];

  expect(getAssistantTurnCopyData(messages)).toBe("Partial answer");
  expect(getAssistantTurnCopyData(messages, { isStreaming: true })).toBeNull();
});

test("marks the latest assistant message as streaming", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Still generating",
    },
  ] as Message[];
  const groups = getMessageGroups(messages);
  const assistantGroupIndex = groups.findIndex(
    (group) => group.type === "assistant",
  );

  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, true, () => ({
        streamMetadata: { langgraph_node: "agent" },
      })),
    ),
  ).toBe(true);
  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, false, () => ({
        streamMetadata: { langgraph_node: "agent" },
      })),
    ),
  ).toBe(false);
});

test("keeps previous assistant copyable while waiting for a new visible answer", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Completed answer",
    },
    {
      id: "opt-human-1",
      type: "human",
      content: "Continue",
    },
  ] as Message[];
  const groups = getMessageGroups(messages);
  const assistantGroupIndex = groups.findIndex(
    (group) => group.type === "assistant",
  );

  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, true),
    ),
  ).toBe(false);
});

test("keeps previous assistant copyable while a hidden send is starting", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Completed answer",
    },
  ] as Message[];
  const groups = getMessageGroups(messages);
  const assistantGroupIndex = groups.findIndex(
    (group) => group.type === "assistant",
  );

  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, true),
    ),
  ).toBe(false);
});

test("keeps previous assistant copyable after a hidden send is appended", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Completed answer",
    },
    {
      id: "human-hidden",
      type: "human",
      content: "Save this agent",
      additional_kwargs: { hide_from_ui: true },
    },
  ] as Message[];
  const groups = getMessageGroups(messages);
  const assistantGroupIndex = groups.findIndex(
    (group) => group.type === "assistant",
  );

  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, true),
    ),
  ).toBe(false);
});

test("uses stream metadata to identify an assistant before optimistic input", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Completed answer",
    },
    {
      id: "ai-2",
      type: "ai",
      content: "Still generating",
    },
    {
      id: "opt-human-1",
      type: "human",
      content: "Continue",
    },
  ] as Message[];
  const assistantGroups = getMessageGroups(messages).filter(
    (group) => group.type === "assistant",
  );
  const groups = getMessageGroups(messages);
  const assistantGroupIndexes = groups
    .map((group, index) => (group.type === "assistant" ? index : -1))
    .filter((index) => index >= 0);

  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndexes[0] ?? -1]?.messages ?? [],
      getStreamingMessageLookup(messages, true, (message) =>
        message.id === "ai-2"
          ? { streamMetadata: { langgraph_node: "agent" } }
          : undefined,
      ),
    ),
  ).toBe(false);
  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndexes[1] ?? -1]?.messages ?? [],
      getStreamingMessageLookup(messages, true, (message) =>
        message.id === "ai-2"
          ? { streamMetadata: { langgraph_node: "agent" } }
          : undefined,
      ),
    ),
  ).toBe(true);
  expect(assistantGroups.map((group) => group.id)).toEqual(["ai-1", "ai-2"]);
});

test("does not mark a completed assistant group streaming from a later processing group", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Visible answer",
    },
    {
      id: "ai-2",
      type: "ai",
      content: "",
      tool_calls: [{ id: "tool-1", name: "web_search", args: {} }],
    },
  ] as Message[];
  const groups = getMessageGroups(messages);
  const assistantGroupIndex = groups.findIndex(
    (group) => group.type === "assistant",
  );

  expect(groups.map((group) => group.type)).toEqual([
    "human",
    "assistant",
    "assistant:processing",
  ]);
  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, true, (message) =>
        message.id === "ai-2"
          ? { streamMetadata: { langgraph_node: "agent" } }
          : undefined,
      ),
    ),
  ).toBe(false);
});

test("keeps streaming assistant hidden when a hidden control message follows it", () => {
  const messages = [
    {
      id: "human-1",
      type: "human",
      content: "Hello",
    },
    {
      id: "ai-1",
      type: "ai",
      content: "Still generating",
    },
    {
      id: "human-hidden",
      type: "human",
      content: "Save this agent",
      additional_kwargs: { hide_from_ui: true },
    },
  ] as Message[];
  const groups = getMessageGroups(messages);
  const assistantGroupIndex = groups.findIndex(
    (group) => group.type === "assistant",
  );

  expect(
    isAssistantMessageGroupStreaming(
      groups[assistantGroupIndex]?.messages ?? [],
      getStreamingMessageLookup(messages, true, (message) =>
        message.id === "ai-1"
          ? { streamMetadata: { langgraph_node: "agent" } }
          : undefined,
      ),
    ),
  ).toBe(true);
});
