import os
from pathlib import Path

from click.testing import CliRunner

from markitect_tool.backend import (
    DependencyEdge,
    SnapshotState,
    load_snapshot_state_file,
    plan_snapshot_refresh,
)
from markitect_tool.cli import main


def test_refresh_plan_marks_all_files_new_without_previous_state(tmp_path: Path):
    source = tmp_path / "doc.md"
    source.write_text("# Doc\n", encoding="utf-8")

    plan = plan_snapshot_refresh([tmp_path], root=tmp_path)

    assert plan.dirty
    assert plan.needs_hash == ["doc.md"]
    assert plan.needs_parse == ["doc.md"]
    assert plan.needs_index == ["doc.md"]


def test_refresh_plan_uses_cheap_metadata_for_unchanged_file(tmp_path: Path):
    source = tmp_path / "doc.md"
    source.write_text("# Doc\n", encoding="utf-8")
    stat = source.stat()
    previous = SnapshotState(
        path="doc.md",
        size=stat.st_size,
        mtime_ns=stat.st_mtime_ns,
        content_hash="sha256:known",
        snapshot_id="snapshot:known",
    )

    plan = plan_snapshot_refresh([tmp_path], previous=[previous], root=tmp_path)

    assert not plan.dirty
    assert plan.unchanged == ["doc.md"]
    assert plan.needs_hash == []


def test_refresh_plan_can_hash_metadata_changed_file_and_skip_parse_if_content_same(tmp_path: Path):
    source = tmp_path / "doc.md"
    source.write_text("# Doc\n", encoding="utf-8")
    stat = source.stat()
    content_hash = _hash_file(source)
    previous = SnapshotState(
        path="doc.md",
        size=stat.st_size,
        mtime_ns=stat.st_mtime_ns,
        content_hash=content_hash,
        snapshot_id="snapshot:known",
    )
    os.utime(source, ns=(stat.st_atime_ns + 1_000_000_000, stat.st_mtime_ns + 1_000_000_000))

    plan = plan_snapshot_refresh(
        [tmp_path],
        previous=[previous],
        root=tmp_path,
        verify_hashes=True,
    )

    assert plan.needs_hash == ["doc.md"]
    assert plan.needs_metadata_update == ["doc.md"]
    assert plan.needs_parse == []
    assert plan.needs_index == []


def test_refresh_plan_invalidates_transitive_dependents(tmp_path: Path):
    source = tmp_path / "source.md"
    dependent = tmp_path / "dependent.md"
    transitive = tmp_path / "transitive.md"
    source.write_text("# Source changed\n", encoding="utf-8")
    dependent.write_text("# Dependent\n", encoding="utf-8")
    transitive.write_text("# Transitive\n", encoding="utf-8")

    source_stat = source.stat()
    dependent_stat = dependent.stat()
    transitive_stat = transitive.stat()
    previous = [
        SnapshotState(
            path="source.md",
            size=1,
            mtime_ns=1,
            content_hash="sha256:old",
            snapshot_id="snapshot:source",
        ),
        SnapshotState(
            path="dependent.md",
            size=dependent_stat.st_size,
            mtime_ns=dependent_stat.st_mtime_ns,
            content_hash=_hash_file(dependent),
            snapshot_id="snapshot:dependent",
            dependencies=[
                DependencyEdge(source_id="snapshot:dependent", target="source.md", kind="reference")
            ],
        ),
        SnapshotState(
            path="transitive.md",
            size=transitive_stat.st_size,
            mtime_ns=transitive_stat.st_mtime_ns,
            content_hash=_hash_file(transitive),
            snapshot_id="snapshot:transitive",
            dependencies=[
                DependencyEdge(source_id="snapshot:transitive", target="dependent.md", kind="reference")
            ],
        ),
    ]

    plan = plan_snapshot_refresh([tmp_path], previous=previous, root=tmp_path)

    assert plan.needs_parse == ["source.md"]
    assert plan.invalidated == ["dependent.md", "transitive.md"]
    entries = {entry.path: entry for entry in plan.entries}
    assert entries["dependent.md"].invalidated_by == ["source.md"]
    assert entries["transitive.md"].invalidated_by == ["dependent.md"]
    assert source_stat.st_size != 1


def test_snapshot_state_file_and_cli_refresh_plan(tmp_path: Path):
    source = tmp_path / "doc.md"
    state_file = tmp_path / "state.yaml"
    source.write_text("# Doc\n", encoding="utf-8")
    stat = source.stat()
    state_file.write_text(
        f"""snapshots:
  - path: doc.md
    size: {stat.st_size}
    mtime_ns: {stat.st_mtime_ns}
    content_hash: {_hash_file(source)}
    snapshot_id: snapshot:known
""",
        encoding="utf-8",
    )

    states = load_snapshot_state_file(state_file)
    result = CliRunner().invoke(
        main,
        [
            "backend",
            "refresh-plan",
            str(tmp_path),
            "--root",
            str(tmp_path),
            "--state",
            str(state_file),
        ],
    )

    assert states[0].path == "doc.md"
    assert result.exit_code == 0
    assert "clean" in result.output
    assert "unchanged: 1" in result.output


def _hash_file(path: Path) -> str:
    import hashlib

    return "sha256:" + hashlib.sha256(path.read_bytes()).hexdigest()