"""Unit: the branch-name validator (phase 135, task 02).

``validate_branch_name`` is the single choke point for every branch
value that enters the API (POST create + PATCH set/change legs —
ASSUMPTION B2). The contract, checked in the documented order (trim →
empty → length → charset → ``..``/``//`` → leading → trailing →
HEAD):

* TRIM first — the returned name is the trimmed input, so a
  schema-trimmed value is a fixed point;
* empty (or whitespace-only) → ``ValueError``;
* > 200 chars → ``ValueError`` (exactly 200 passes — the schema's
  ``max_length=200`` is the first line, the validator the choke point
  a future caller must not bypass);
* outside the safe charset ``[A-Za-z0-9._/-]+`` → ``ValueError``
  (whitespace, ``@``, ``~``, ``^``, ``:``, ``?``, ``*``, ``[``,
  backslash — all out);
* contains ``..`` or ``//`` → ``ValueError`` (path-traversal-shaped
  names, even though the charset would allow the pieces);
* leading ``-`` / ``.`` / ``/`` → ``ValueError``;
* trailing ``/`` or ``.`` → ``ValueError``;
* ``HEAD`` (any case) → ``ValueError`` (git's refname — a branch
  literally named ``head`` is a documented cost of the simple rule).

The raised ``ValueError`` messages are FIXED reason strings — the
API maps them to the fixed-detail 422 and the raw input is never
echoed (the house credential-safety discipline, applied for
consistency): the tests pin that no message repeats the rejected
input.
"""
from __future__ import annotations

import pytest

from app.rag.git_sources import validate_branch_name

# ---------------------------------------------------------------------------
# Accept
# ---------------------------------------------------------------------------


@pytest.mark.parametrize(
    "raw",
    [
        "main",
        "release/1.2",
        "feature_x",
        "a.b/c",
        "v2-rc.1",
    ],
)
def test_valid_names_pass_through_trimmed(raw: str) -> None:
    """The accepted shapes — plain, slashed, dotted, dashed,
    underscored — return exactly the trimmed input."""
    assert validate_branch_name(raw) == raw


def test_trim_applied_before_validation_and_returned() -> None:
    """Surrounding whitespace is stripped: the returned value is the
    trimmed name (``"  main  "`` → ``main``)."""
    assert validate_branch_name("  main  ") == "main"
    assert validate_branch_name("\trelease/1.2\n") == "release/1.2"


def test_exactly_200_chars_passes() -> None:
    """The length boundary is > 200: a 200-char name is valid
    (the charset allows it — a long but well-formed branch path)."""
    name = "a" * 196 + "/x.1"
    assert len(name) == 200
    assert validate_branch_name(name) == name


# ---------------------------------------------------------------------------
# Reject
# ---------------------------------------------------------------------------


@pytest.mark.parametrize(
    "raw",
    [
        "",
        "   ",
        "a b",  # whitespace inside
        "a@b",
        "a~b",
        "a:b",
        "a?b",
        "a*b",
        "a[b",
        "a\\b",
        "a^b",
    ],
)
def test_empty_and_charset_violations_rejected(raw: str) -> None:
    """Empty/whitespace-only and non-charset characters all raise."""
    with pytest.raises(ValueError):
        validate_branch_name(raw)


def test_201_chars_rejected() -> None:
    """One past the length limit raises (even though the charset
    allows every character)."""
    with pytest.raises(ValueError):
        validate_branch_name("a" * 201)


@pytest.mark.parametrize("raw", ["a..b", "a//b", "..", "//"])
def test_path_sequences_rejected(raw: str) -> None:
    """``..`` and ``//`` are disallowed — traversal-shaped names,
    including the two-character bare forms."""
    with pytest.raises(ValueError):
        validate_branch_name(raw)


@pytest.mark.parametrize("raw", ["-x", ".x", "/x"])
def test_leading_characters_rejected(raw: str) -> None:
    """A leading ``-`` (git would read it as an option), ``.``, or
    ``/`` raises."""
    with pytest.raises(ValueError):
        validate_branch_name(raw)


@pytest.mark.parametrize("raw", ["x/", "x."])
def test_trailing_characters_rejected(raw: str) -> None:
    """A trailing ``/`` or ``.`` raises."""
    with pytest.raises(ValueError):
        validate_branch_name(raw)


@pytest.mark.parametrize("raw", ["HEAD", "head", "HeAd", " hEaD "])
def test_head_rejected_case_insensitively(raw: str) -> None:
    """``HEAD`` in any case is git's refname — rejected (the trim runs
    first, so even `` hEaD `` is the reserved name)."""
    with pytest.raises(ValueError):
        validate_branch_name(raw)


def test_reject_messages_are_fixed_and_input_free() -> None:
    """The ``ValueError`` reasons are fixed strings — none of them
    echoes the rejected input (the API maps to the fixed-detail 422
    on the same discipline; a secret-ish name typed into the field
    must not surface in a log line either)."""
    for raw in ("a b", "a..b", "x/", "HEAD", "a" * 201, ""):
        try:
            validate_branch_name(raw)
        except ValueError as e:
            if raw:
                assert raw not in str(e)
        else:
            pytest.fail(f"{raw!r} must be rejected")