"""Unit tests for lore_commands' pure compaction transforms.

Heavy imports (discord, ai_functions, constants side effects) are stubbed only
when genuinely absent, matching the pytest-only unit CI job.
"""
import sys
import types


def _stub_if_missing(name, build):
    if name in sys.modules:
        return
    try:
        __import__(name)
    except ImportError:
        sys.modules[name] = build()


def _build_discord():
    mod = types.ModuleType("discord")

    class Object:
        def __init__(self, id=None):  # noqa: A002
            self.id = id

    class Member:
        pass

    mod.Object = Object
    mod.Member = Member
    ext = types.ModuleType("discord.ext")
    commands = types.ModuleType("discord.ext.commands")

    class Cog:
        pass

    def _passthrough(*_a, **_k):
        return lambda fn: fn

    commands.Cog = Cog
    commands.hybrid_command = _passthrough
    tasks = types.ModuleType("discord.ext.tasks")
    commands_tasks = types.ModuleType("_")

    def loop(**_k):
        def deco(fn):
            fn.before_loop = lambda f: f
            return fn
        return deco

    tasks.loop = loop
    commands.tasks = tasks
    ext.commands = commands
    ext.tasks = tasks
    mod.ext = ext
    sys.modules["discord.ext"] = ext
    sys.modules["discord.ext.commands"] = commands
    sys.modules["discord.ext.tasks"] = tasks
    return mod


def _build_ai_functions():
    mod = types.ModuleType("ai_functions")

    async def handle_response(*_a, **_k):
        return ("legenda stub", [])

    mod.handle_response = handle_response
    return mod


_stub_if_missing("discord", _build_discord)
_stub_if_missing("ai_functions", _build_ai_functions)

import lore_commands  # noqa: E402  (after stubbing)


def _msgs(n):
    return [{"role": "user" if i % 2 == 0 else "assistant", "content": f"m{i}"} for i in range(n)]


def test_apply_compaction_replaces_prefix_keeps_tail():
    messages = _msgs(10)
    result = lore_commands.apply_compaction(messages, old_count=6, legend_text="LEGENDA")
    # one legend system-message, then the last 4 verbatim
    assert result[0]["role"] == "system"
    assert result[0]["content"].endswith("LEGENDA")
    assert [m["content"] for m in result[1:]] == ["m6", "m7", "m8", "m9"]
    assert len(result) == 5


def test_apply_compaction_preserves_appends_made_during_summarize():
    # Simulate: we decided old_count on a 10-message file, but by write time two
    # more messages were appended (a chat happened during the AI call). Those
    # tail appends must survive.
    grown = _msgs(10) + [{"role": "user", "content": "new1"}, {"role": "assistant", "content": "new2"}]
    result = lore_commands.apply_compaction(grown, old_count=6, legend_text="L")
    tail = [m["content"] for m in result[1:]]
    assert tail == ["m6", "m7", "m8", "m9", "new1", "new2"]


def test_build_transcript_formats_lines():
    text = lore_commands.build_transcript(
        [{"role": "user", "content": "cześć"}, {"role": "assistant", "content": "no elo"}]
    )
    assert text == "user: cześć\nassistant: no elo"


def test_build_transcript_skips_empty_and_truncates():
    text = lore_commands.build_transcript(
        [{"role": "user", "content": "x" * 20000}, {"role": "assistant", "content": ""}],
        max_chars=1000,
    )
    assert "[...urwane...]" in text
    assert len(text) <= 1000 + len("\n[...urwane...]\n")