"""`hermes skin set` — deterministic single-color tweak of the active skin.

The whole point is that changing one token never disturbs the rest of the look
(background especially), which hand-authoring kept getting wrong.
"""

import os

import pytest
import yaml

from hermes_cli import skin_cmd
from hermes_constants import get_hermes_home


def _skins():
    d = get_hermes_home() / "skins"
    d.mkdir(parents=True, exist_ok=True)
    return d


def _activate(name: str) -> None:
    (get_hermes_home() / "config.yaml").write_text(f"display:\n  skin: {name}\n", encoding="utf-8")


def test_set_edits_active_user_skin_in_place_preserving_everything_else():
    (_skins() / "oasis.yaml").write_text(
        'name: oasis\ncolors:\n  background: "#08201f"\n  banner_title: "#f2dfb3"\n', encoding="utf-8"
    )
    _activate("oasis")

    assert skin_cmd._skin_set("ui_tool", "#00FFFF", None) == 0

    data = yaml.safe_load((_skins() / "oasis.yaml").read_text())
    assert data["colors"]["ui_tool"] == "#00FFFF"
    assert data["colors"]["background"] == "#08201f"  # untouched — the whole point
    assert data["colors"]["banner_title"] == "#f2dfb3"
    assert data["name"] == "oasis"  # no rename, no fork
    assert not (_skins() / "oasis-custom.yaml").exists()


def test_set_forks_a_builtin_without_inventing_a_background():
    _activate("default")  # a built-in — no file

    assert skin_cmd._skin_set("ui_tool", "#00FFFF", None) == 0

    fork = _skins() / "default-custom.yaml"
    assert fork.exists()
    data = yaml.safe_load(fork.read_text())
    assert data["colors"]["ui_tool"] == "#00FFFF"
    # default has no background, so the fork must not invent one (terminal stays put).
    assert "background" not in data["colors"]
    # full palette carried over, and it became active.
    assert data["colors"].get("banner_title")
    assert (get_hermes_home() / "config.yaml").read_text().find("default-custom") != -1


def test_set_rejects_non_hex():
    _activate("default")
    assert skin_cmd._skin_set("ui_tool", "teal", None) == 1


def test_set_persists_the_skin_durably():
    """The palette must reach disk before ``skin set`` returns.

    ``write_text`` truncates and writes without ever calling ``fsync``, so a
    power loss or container kill right after the command "succeeds" can leave
    ``<skin>.yaml`` zero-length.  That is not transient: ``_skin_set`` is a
    read-modify-write and ``safe_load("")`` returns ``None``, which its
    ``or {}`` turns into an empty palette — so the next tweak rewrites the
    file from that empty state and the rest of the palette is gone for good.
    The gateway's skin watcher repaints every live surface from this file
    within ~1s either way.
    """
    path = _skins() / "oasis.yaml"
    path.write_text(
        'name: oasis\ncolors:\n  background: "#08201f"\n  banner_title: "#f2dfb3"\n',
        encoding="utf-8",
    )
    _activate("oasis")

    synced = []
    real_fsync = os.fsync

    def _tracking_fsync(fd):
        synced.append(fd)
        return real_fsync(fd)

    with pytest.MonkeyPatch.context() as mp:
        mp.setattr(os, "fsync", _tracking_fsync)
        assert skin_cmd._skin_set("ui_tool", "#00FFFF", None) == 0

    assert synced, "skin file written without fsync — a crash can leave it empty"

    data = yaml.safe_load(path.read_text(encoding="utf-8"))
    assert data["colors"]["ui_tool"] == "#00FFFF"
    assert data["colors"]["background"] == "#08201f"  # untouched — the whole point
    assert data["colors"]["banner_title"] == "#f2dfb3"
    assert [p.name for p in _skins().iterdir() if p.name.endswith(".tmp")] == []


def test_set_preserves_a_symlinked_skin_file():
    """Guard on the conversion, not a behavior change.

    ``write_text`` wrote through a symlink; a naive ``os.replace`` would
    detach it.  ``atomic_replace`` resolves the link first (GitHub #16743),
    so a skin file symlinked out to a dotfiles repo must stay a symlink.
    """
    real_dir = _skins().parent / "dotfiles"
    real_dir.mkdir(parents=True, exist_ok=True)
    real = real_dir / "oasis.yaml"
    real.write_text(
        'name: oasis\ncolors:\n  background: "#08201f"\n', encoding="utf-8"
    )
    link = _skins() / "oasis.yaml"
    link.symlink_to(real)
    _activate("oasis")

    assert skin_cmd._skin_set("ui_tool", "#00FFFF", None) == 0

    assert link.is_symlink()
    data = yaml.safe_load(real.read_text(encoding="utf-8"))
    assert data["colors"]["ui_tool"] == "#00FFFF"
    assert data["colors"]["background"] == "#08201f"