"""Unit tests: importer directory walk + sha256 delta logic.

The walk tests are pure filesystem (``tmp_path``); the delta tests run
against the local compose Postgres (preferred — a real vector table),
skipping with clear instructions when the stack is not up.
"""
from __future__ import annotations

import asyncio
from pathlib import Path

import pytest
from sqlalchemy import func, select

from app.models import Chunk, Document
from app.rag.importer import (
    EXCLUDED_DIRS,
    import_sources,
    iter_markdown_files,
)
from app.rag.llm import EmbeddingError
from tests.fakes import FakeEmbedder


class _PoisonEmbedder(FakeEmbedder):
    """Fails (like a real endpoint) on any text containing 'poison'."""

    async def embed(self, texts: list[str]) -> list[list[float]]:
        if any("poison" in t for t in texts):
            raise EmbeddingError("embeddings endpoint refused the input (simulated)")
        return await super().embed(texts)


class _CapEmbedder(FakeEmbedder):
    """Simulates the endpoint's ~1024-token input cap at ~1.1 chars/token:
    any single text over 1000 chars is rejected (URL-dense worst case)."""

    async def embed(self, texts: list[str]) -> list[list[float]]:
        if any(len(t) > 1000 for t in texts):
            raise EmbeddingError(
                "a single 1100-char chunk exceeded the endpoint's per-request "
                "input token cap — lower BOR_CHUNK_TARGET_CHARS and re-import"
            )
        return await super().embed(texts)


def _cleanup_source(db, source: str) -> None:
    for doc in db.scalars(select(Document).where(Document.source == source)).all():
        db.delete(doc)
    db.commit()


def test_iter_markdown_files_excludes_noncontent_dirs(tmp_path: Path) -> None:
    root = tmp_path / "proj"
    for d in (
        "notes/sub",
        ".venv/lib",
        "node_modules/x",
        ".git",
        "__pycache__",
        ".pytest_cache",
        "dist",
        "build",
    ):
        (root / d).mkdir(parents=True)
    files = {
        "README.md": "readme",
        "notes/sub/deep.md": "deep",
        ".venv/lib/junk.md": "junk",
        "node_modules/x/j.md": "j",
        ".git/c.md": "g",
        "__pycache__/c.md": "p",
        ".pytest_cache/c.md": "pc",
        "dist/d.md": "d",
        "build/b.md": "b",
    }
    for rel, text in files.items():
        (root / rel).write_text(text)
    (root / "notes" / "not-md.txt").write_text("skip me")

    found = {p.relative_to(root).as_posix() for p in iter_markdown_files(root)}
    assert found == {"README.md", "notes/sub/deep.md"}


def test_iter_markdown_files_missing_dir_yields_nothing(tmp_path: Path) -> None:
    assert iter_markdown_files(tmp_path / "definitely-missing") == []


def test_excluded_dirs_match_plan_anchor_a9() -> None:
    assert {
        ".venv", "node_modules", ".git", "__pycache__", ".pytest_cache", "dist", "build"
    } == EXCLUDED_DIRS


def test_added_then_unchanged_then_updated_then_pruned(db, tmp_path: Path) -> None:
    root = tmp_path / "src"
    root.mkdir()
    (root / "a.md").write_text("# A\n\nalpha\n\n## Sub\n\nmore alpha\n")
    (root / "b.md").write_text("# B\n\nbeta\n")
    llm = FakeEmbedder()
    try:
        s1 = asyncio.run(import_sources([root], llm, session=db))
        assert (s1.files, s1.added, s1.unchanged, s1.updated, s1.pruned) == (2, 2, 0, 0, 0)
        # a.md has two sections (2 chunks), b.md one (1 chunk).
        assert s1.chunks == 3
        # Embeddings are stored with the configured dimension.
        n = db.scalar(
            select(func.count())
            .select_from(Chunk)
            .join(Document, Document.id == Chunk.document_id)
            .where(Document.source == root.name)
        )
        assert n == 3
        for c in db.scalars(
            select(Chunk)
            .join(Document, Document.id == Chunk.document_id)
            .where(Document.source == root.name)
        ).all():
            assert c.embedding is not None and len(c.embedding) == 768

        s2 = asyncio.run(import_sources([root], llm, session=db))
        assert s2.added == 0 and s2.unchanged == 2

        (root / "a.md").write_text("# A\n\nalpha CHANGED\n")
        s3 = asyncio.run(import_sources([root], llm, session=db))
        assert s3.updated == 1 and s3.unchanged == 1
        doc = db.scalar(
            select(Document).where(Document.source == root.name, Document.path == "a.md")
        )
        assert doc is not None and "CHANGED" in doc.content

        (root / "a.md").unlink()
        s4 = asyncio.run(import_sources([root], llm, session=db, prune=True))
        assert s4.pruned == 1
        assert db.scalar(
            select(Document).where(Document.source == root.name, Document.path == "a.md")
        ) is None
        # Chunks of the pruned document are gone (FK cascade).
        n_after = db.scalar(
            select(func.count())
            .select_from(Chunk)
            .join(Document, Document.id == Chunk.document_id)
            .where(Document.source == root.name)
        )
        assert n_after == 1
    finally:
        _cleanup_source(db, root.name)


def test_embedding_failure_is_logged_and_import_continues(db, tmp_path: Path) -> None:
    """A file the embedding endpoint refuses must not abort the whole KB:
    its rows are rolled back, the error is counted, and other files import."""
    root = tmp_path / "mixed"
    root.mkdir()
    (root / "bad.md").write_text("# Bad\n\npoison content that the endpoint refuses\n")
    (root / "good.md").write_text("# Good\n\nperfectly fine content\n")
    try:
        summary = asyncio.run(import_sources([root], _PoisonEmbedder(), session=db))
        assert summary.files == 2
        assert summary.errors == 1
        assert summary.added == 1  # only good.md
        # bad.md left no row and no orphan chunks behind (rolled back).
        assert db.scalar(
            select(Document).where(Document.source == root.name, Document.path == "bad.md")
        ) is None
        assert db.scalar(
            select(func.count())
            .select_from(Chunk)
            .join(Document, Document.id == Chunk.document_id)
            .where(Document.source == root.name, Document.path == "bad.md")
        ) == 0
        assert db.scalar(
            select(Document).where(Document.source == root.name, Document.path == "good.md")
        ) is not None
    finally:
        _cleanup_source(db, root.name)


def test_oversized_chunk_triggers_adaptive_rechunk(db, tmp_path: Path) -> None:
    """A URL-dense paragraph the endpoint rejects must be re-chunked smaller
    for that file only — the import still succeeds."""
    root = tmp_path / "dense"
    root.mkdir()
    # One ~1165-char paragraph: under the 1200-char hard cap, over the
    # simulated token cap. The retry at 600 chars must split it.
    para = "see https://example.com/" + "a" * 1100
    (root / "dense.md").write_text(f"# D\n\n{para}\n")
    try:
        summary = asyncio.run(import_sources([root], _CapEmbedder(), session=db))
        assert summary.errors == 0
        assert summary.added == 1
        doc = db.scalar(
            select(Document).where(Document.source == root.name, Document.path == "dense.md")
        )
        assert doc is not None
        assert len(doc.chunks) >= 2  # re-chunked smaller than the hard cap
        assert all(len(c.content) <= 1000 for c in doc.chunks)
        assert all(c.embedding is not None for c in doc.chunks)
        # The content survives the split.
        assert "".join(c.content for c in doc.chunks).count("a" * 500) >= 1
    finally:
        _cleanup_source(db, root.name)


def test_missing_source_dir_is_skipped(db, tmp_path: Path) -> None:
    llm = FakeEmbedder()
    summary = asyncio.run(import_sources([tmp_path / "missing"], llm, session=db))
    assert summary.files == 0 and summary.added == 0


def test_limit_caps_files_and_disables_prune(db, tmp_path: Path) -> None:
    root = tmp_path / "limited"
    root.mkdir()
    for name in ("a.md", "b.md", "c.md"):
        (root / name).write_text(f"# {name}\n\nbody {name}\n")
    llm = FakeEmbedder()
    try:
        summary = asyncio.run(import_sources([root], llm, limit=2, session=db, prune=True))
        assert summary.files == 2 and summary.added == 2
        # c.md was never walked, so it must NOT be pruned (prune disabled
        # under --limit) — and nothing else disappears either.
        assert summary.pruned == 0
        assert db.scalar(
            select(func.count()).select_from(Document).where(Document.source == root.name)
        ) == 2
    finally:
        _cleanup_source(db, root.name)


def test_limit_must_be_positive(db, tmp_path: Path) -> None:
    with pytest.raises(ValueError):
        asyncio.run(import_sources([tmp_path], FakeEmbedder(), limit=0, session=db))


def test_prune_is_scoped_to_the_given_sources(db, tmp_path: Path) -> None:
    src_x = tmp_path / "SourceX"
    src_y = tmp_path / "SourceY"
    src_x.mkdir()
    src_y.mkdir()
    (src_x / "x.md").write_text("# X\n\nx body\n")
    (src_y / "y.md").write_text("# Y\n\ny body\n")
    llm = FakeEmbedder()
    try:
        asyncio.run(import_sources([src_x, src_y], llm, session=db))
        # Re-import ONLY source Y (y.md removed) with prune: source X's doc
        # must survive — prune never touches sources not passed to this run.
        (src_y / "y.md").unlink()
        summary = asyncio.run(import_sources([src_y], llm, session=db, prune=True))
        assert summary.pruned == 1
        assert db.scalar(
            select(Document).where(Document.source == "SourceX", Document.path == "x.md")
        ) is not None
    finally:
        _cleanup_source(db, "SourceX")
        _cleanup_source(db, "SourceY")


def test_chunk_positions_and_titles(db, tmp_path: Path) -> None:
    root = tmp_path / "titled"
    root.mkdir()
    (root / "multi.md").write_text("# Real Title\n\n## One\n\na\n\n## Two\n\nb\n")
    (root / "noh1.md").write_text("## Only heading\n\nbody\n")
    llm = FakeEmbedder()
    try:
        asyncio.run(import_sources([root], llm, session=db))
        titles = {
            d.path: d.title
            for d in db.scalars(select(Document).where(Document.source == root.name)).all()
        }
        assert titles["multi.md"] == "Real Title"  # H1 wins
        assert titles["noh1.md"] == "noh1"  # …else the file stem
        doc = db.scalar(
            select(Document).where(Document.source == root.name, Document.path == "multi.md")
        )
        assert doc is not None
        positions = sorted(c.position for c in doc.chunks)
        assert positions == list(range(len(doc.chunks))) and len(doc.chunks) >= 2
    finally:
        _cleanup_source(db, root.name)