from __future__ import annotations

import re

from headroom.transforms.compression_batches import (
    CompressionBatchEntry,
    build_compression_batches,
    compress_batch_with_router,
)
from headroom.transforms.compression_units import CompressionUnit, RoutedCompressionUnit
from headroom.transforms.content_router import CompressionStrategy, RouterCompressionResult


def _entry(index: int, text: str) -> CompressionBatchEntry:
    unit = CompressionUnit(
        text=text,
        provider="openai",
        endpoint="responses",
        role="tool",
        item_type="local_shell_call_output",
        cache_zone="live",
        mutable=True,
        min_bytes=512,
    )
    return CompressionBatchEntry(
        entry_id=f"u{index}",
        routed=RoutedCompressionUnit(unit=unit, slot=(index, ("output", None))),
    )


def test_small_units_over_floor_form_one_batch():
    entries = [_entry(index, "x" * 150) for index in range(4)]

    batches, skipped = build_compression_batches(entries, min_batch_bytes=512)

    assert len(batches) == 1
    assert [entry.entry_id for entry in batches[0].entries] == ["u0", "u1", "u2", "u3"]
    assert batches[0].text_bytes == 600
    assert skipped == []


class _CharacterCounter:
    def count_text(self, text: str) -> int:
        return len(text)


class _ShorteningRouter:
    def __init__(self) -> None:
        self.calls = 0

    def compress(self, content: str, **_kwargs) -> RouterCompressionResult:
        self.calls += 1
        return RouterCompressionResult(
            compressed=content.replace("x" * 150, "x"),
            original=content,
            strategy_used=CompressionStrategy.KOMPRESS,
        )


def test_batch_compresses_entries_with_one_router_call():
    entries = [_entry(index, "x" * 150) for index in range(4)]
    batches, _ = build_compression_batches(entries, min_batch_bytes=512)
    router = _ShorteningRouter()

    results = compress_batch_with_router(
        batches[0],
        router=router,
        tokenizer=_CharacterCounter(),
    )

    assert router.calls == 1
    assert [slot for slot, _ in results] == [entry.routed.slot for entry in entries]
    assert [result.compressed for _, result in results] == ["x"] * 4
    assert all(result.modified for _, result in results)


def test_under_floor_tail_is_skipped_without_a_batch():
    entries = [_entry(index, "x" * 150) for index in range(3)]

    batches, skipped = build_compression_batches(entries, min_batch_bytes=512)

    assert batches == []
    assert [entry.entry_id for entry in skipped] == ["u0", "u1", "u2"]


def test_sixteen_under_floor_entries_are_skipped_before_a_new_batch_starts():
    entries = [_entry(index, "x" * 30) for index in range(17)]

    batches, skipped = build_compression_batches(entries, min_batch_bytes=512)

    assert batches == []
    assert [entry.entry_id for entry in skipped] == [f"u{index}" for index in range(17)]


class _CorruptingRouter:
    def compress(self, content: str, **_kwargs) -> RouterCompressionResult:
        return RouterCompressionResult(
            compressed="missing protected tags",
            original=content,
            strategy_used=CompressionStrategy.KOMPRESS,
        )


def test_missing_batch_tags_passes_through_every_entry():
    entries = [_entry(index, "x" * 150) for index in range(4)]
    batches, _ = build_compression_batches(entries, min_batch_bytes=512)

    results = compress_batch_with_router(
        batches[0],
        router=_CorruptingRouter(),
        tokenizer=_CharacterCounter(),
    )

    assert [result.compressed for _, result in results] == ["x" * 150] * 4
    assert [result.reason for _, result in results] == ["batch_invalid"] * 4
    assert not any(result.modified for _, result in results)


def test_many_small_entries_create_no_more_than_sixteen_per_batch():
    entries = [_entry(index, "x" * 100) for index in range(381)]

    batches, skipped = build_compression_batches(entries, min_batch_bytes=512)

    assert skipped == []
    assert len(batches) <= 24
    assert all(len(batch.entries) <= 16 for batch in batches)
    assert all(batch.text_bytes <= 2048 for batch in batches)


class _LossyShellRouter:
    def compress(self, content: str, **_kwargs) -> RouterCompressionResult:
        return RouterCompressionResult(
            compressed=content.replace("line alpha beta gamma\n" * 7, "summary"),
            original=content,
            strategy_used=CompressionStrategy.KOMPRESS,
        )


def test_batch_keeps_structured_shell_output_without_a_ccr_marker():
    entries = [_entry(index, "line alpha beta gamma\n" * 7) for index in range(4)]
    batches, _ = build_compression_batches(entries, min_batch_bytes=512)

    results = compress_batch_with_router(
        batches[0],
        router=_LossyShellRouter(),
        tokenizer=_CharacterCounter(),
    )

    assert not any(result.modified for _, result in results)
    assert [result.reason for _, result in results] == ["lossy_unrecoverable_tool_output"] * 4


class _MarkerStrippingRouter:
    def compress(self, content: str, **_kwargs) -> RouterCompressionResult:
        return RouterCompressionResult(
            compressed=content.replace("word " * 30, "x").replace(
                "[100 items compressed to 10. Retrieve more: hash=abc123]", ""
            ),
            original=content,
            strategy_used=CompressionStrategy.KOMPRESS,
        )


def test_batch_preserves_ccr_markers_when_router_would_remove_them():
    marker = "[100 items compressed to 10. Retrieve more: hash=abc123]"
    original = f"{'word ' * 30}\n{marker}\n"
    entries = [_entry(index, original) for index in range(4)]
    batches, _ = build_compression_batches(entries, min_batch_bytes=512)

    results = compress_batch_with_router(
        batches[0],
        router=_MarkerStrippingRouter(),
        tokenizer=_CharacterCounter(),
    )

    assert all(result.modified for _, result in results)
    assert all(marker in result.compressed for _, result in results)


class _MarkerMovingRouter:
    def compress(self, content: str, **_kwargs) -> RouterCompressionResult:
        placeholders = re.findall(r"\[\[HEADROOM_BATCH_CCR_[^]]+\]\]", content)
        moved = content.replace(placeholders[0], "", 1).replace(
            placeholders[1], f"{placeholders[1]}{placeholders[0]}", 1
        )
        return RouterCompressionResult(
            compressed=moved.replace("word " * 30, "x"),
            original=content,
            strategy_used=CompressionStrategy.KOMPRESS,
        )


def test_batch_rejects_ccr_marker_moved_to_another_entry():
    marker = "[100 items compressed to 10. Retrieve more: hash=abc123]"
    original = f"{'word ' * 30}\n{marker}\n"
    entries = [_entry(index, original) for index in range(4)]
    batches, _ = build_compression_batches(entries, min_batch_bytes=512)

    results = compress_batch_with_router(
        batches[0],
        router=_MarkerMovingRouter(),
        tokenizer=_CharacterCounter(),
    )

    assert [result.compressed for _, result in results] == [original] * 4
    assert [result.reason for _, result in results] == ["batch_invalid"] * 4


class _CjkShorteningRouter:
    def compress(self, content: str, **_kwargs) -> RouterCompressionResult:
        return RouterCompressionResult(
            compressed=content.replace("你" * 150, "短"),
            original=content,
            strategy_used=CompressionStrategy.KOMPRESS,
        )


def test_batch_uses_utf8_bytes_for_cjk_small_units():
    entries = [_entry(index, "你" * 150) for index in range(4)]

    batches, skipped = build_compression_batches(entries, min_batch_bytes=512)
    results = compress_batch_with_router(
        batches[0],
        router=_CjkShorteningRouter(),
        tokenizer=_CharacterCounter(),
    )

    assert skipped == []
    assert batches[0].text_bytes == 1800
    assert all(result.modified for _, result in results)
    assert [result.compressed for _, result in results] == ["短"] * 4