"""
Tests for the version-chain diff endpoint added in DSMS Stufe 3.

Mocks ipfs_cat so the test does not require a running IPFS node.
"""

import base64
import json
from unittest.mock import AsyncMock, patch

import pytest
from fastapi.testclient import TestClient

from main import app

client = TestClient(app)


def _wrap(metadata: dict, content_text: str) -> str:
    """Mimic the JSON envelope that routers.documents.ipfs_cat returns."""
    return json.dumps(
        {
            "metadata": metadata,
            "content_base64": base64.b64encode(content_text.encode("utf-8")).decode("ascii"),
        }
    )


@pytest.mark.asyncio
async def test_diff_text_documents_returns_unified_diff():
    pkg_a = _wrap({"version": "1", "document_type": "ce_techfile"}, "alpha\nbeta\ngamma\n")
    pkg_b = _wrap({"version": "2", "document_type": "ce_techfile"}, "alpha\nDELTA\ngamma\n")

    async def fake_cat(cid: str):
        return pkg_a if cid == "cidA" else pkg_b

    with patch("routers.documents.ipfs_cat", new=AsyncMock(side_effect=fake_cat)):
        resp = client.get("/api/v1/documents/cidA/diff/cidB")

    assert resp.status_code == 200
    body = resp.json()
    assert body["kind"] == "text"
    assert body["cid_a"] == "cidA"
    assert body["cid_b"] == "cidB"
    assert body["added_lines"] >= 1
    assert body["removed_lines"] >= 1
    assert "DELTA" in body["diff"]
    assert body["metadata_diff"] == {"version": {"old": "1", "new": "2"}}


@pytest.mark.asyncio
async def test_diff_binary_documents_returns_metadata_only():
    # Use raw bytes that are not utf-8 decodable
    invalid_utf8 = b"\xff\xfe\xfd\xfc"
    pkg_a = json.dumps(
        {"metadata": {"version": "1"}, "content_base64": base64.b64encode(invalid_utf8).decode()}
    )
    pkg_b = json.dumps(
        {"metadata": {"version": "2"}, "content_base64": base64.b64encode(invalid_utf8 + b"\x00").decode()}
    )

    async def fake_cat(cid: str):
        return pkg_a if cid == "cidA" else pkg_b

    with patch("routers.documents.ipfs_cat", new=AsyncMock(side_effect=fake_cat)):
        resp = client.get("/api/v1/documents/cidA/diff/cidB")

    assert resp.status_code == 200
    body = resp.json()
    assert body["kind"] == "binary"
    assert body["metadata_diff"] == {"version": {"old": "1", "new": "2"}}


@pytest.mark.asyncio
async def test_diff_handles_fetch_error():
    async def fake_cat(cid: str):
        raise RuntimeError("not pinned")

    with patch("routers.documents.ipfs_cat", new=AsyncMock(side_effect=fake_cat)):
        resp = client.get("/api/v1/documents/cidA/diff/cidB")

    assert resp.status_code == 200
    body = resp.json()
    assert "error" in body
    assert body["cid_a"] == "cidA"
    assert body["cid_b"] == "cidB"


@pytest.mark.asyncio
async def test_history_endpoint_follows_parent_chain():
    """Sanity check that the existing history endpoint still works after route alias."""

    chain = {
        "v3": _wrap({"version": "3", "parent_cid": "v2"}, "x"),
        "v2": _wrap({"version": "2", "parent_cid": "v1"}, "x"),
        "v1": _wrap({"version": "1", "parent_cid": None}, "x"),
    }

    async def fake_cat(cid: str):
        return chain[cid]

    with patch("routers.documents.ipfs_cat", new=AsyncMock(side_effect=fake_cat)):
        resp = client.get("/api/v1/documents/v3/history")

    assert resp.status_code == 200
    body = resp.json()
    assert body["depth"] == 3
    assert [h["version"] for h in body["history"]] == ["3", "2", "1"]