"""
Unit tests for LongTextProcessStage (longtext) pipeline stage.

Tests cover:
- Strategy selection (none/image/forward)
- Threshold boundary handling
- Plain/non-Plain component handling
- Strategy initialization and process
"""

from __future__ import annotations

import pytest
from unittest.mock import AsyncMock, Mock
from importlib import import_module

from tests.factories import (
    FakeApp,
    text_query,
)

import langbot_plugin.api.entities.builtin.platform.message as platform_message


def get_longtext_module():
    """Lazy import to avoid circular import issues."""
    # Import pipelinemgr first to trigger stage registration
    import_module('langbot.pkg.pipeline.pipelinemgr')
    return import_module('langbot.pkg.pipeline.longtext.longtext')


def get_strategy_module():
    """Lazy import for strategy base."""
    return import_module('langbot.pkg.pipeline.longtext.strategy')


def get_entities_module():
    """Lazy import for pipeline entities."""
    return import_module('langbot.pkg.pipeline.entities')


def make_longtext_config(strategy: str = 'none', threshold: int = 1000):
    """Create a pipeline config for long text processing."""
    return {
        'output': {
            'long-text-processing': {
                'strategy': strategy,
                'threshold': threshold,
                'font-path': '/nonexistent/font.ttf',  # For image strategy
            }
        }
    }


class TestLongTextProcessStageInit:
    """Tests for LongTextProcessStage initialization."""

    @pytest.mark.asyncio
    async def test_initialize_none_strategy(self):
        """Initialize with strategy='none' should set strategy_impl to None."""
        longtext = get_longtext_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        pipeline_config = make_longtext_config(strategy='none')

        await stage.initialize(pipeline_config)

        assert stage.strategy_impl is None

    @pytest.mark.asyncio
    async def test_initialize_forward_strategy(self):
        """Initialize with strategy='forward' should use ForwardComponentStrategy."""
        longtext = get_longtext_module()
        strategy = get_strategy_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        pipeline_config = make_longtext_config(strategy='forward')

        await stage.initialize(pipeline_config)

        assert stage.strategy_impl is not None
        assert isinstance(stage.strategy_impl, strategy.LongTextStrategy)

    @pytest.mark.asyncio
    async def test_initialize_unknown_strategy_raises(self):
        """Initialize with unknown strategy should raise ValueError."""
        longtext = get_longtext_module()
        strategy = get_strategy_module()

        # Save original preregistered_strategies
        original_strategies = strategy.preregistered_strategies.copy()

        try:
            # Clear registered strategies to simulate unknown
            strategy.preregistered_strategies = []

            app = FakeApp()
            stage = longtext.LongTextProcessStage(app)

            pipeline_config = make_longtext_config(strategy='unknown')

            with pytest.raises(ValueError, match='Long message processing strategy not found'):
                await stage.initialize(pipeline_config)
        finally:
            # Restore original strategies
            strategy.preregistered_strategies = original_strategies


class TestLongTextProcessStageProcess:
    """Tests for LongTextProcessStage process behavior."""

    @pytest.mark.asyncio
    async def test_none_strategy_continues(self):
        """strategy='none' should always continue."""
        longtext = get_longtext_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        pipeline_config = make_longtext_config(strategy='none')

        await stage.initialize(pipeline_config)

        query = text_query("hello")
        query.pipeline_config = pipeline_config
        query.resp_message_chain = [
            platform_message.MessageChain([platform_message.Plain(text="very long response")])
        ]

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        assert result.new_query is not None

    @pytest.mark.asyncio
    async def test_short_text_continues_without_transform(self):
        """Text shorter than threshold should not be transformed."""
        longtext = get_longtext_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        # High threshold so text won't trigger transform
        pipeline_config = make_longtext_config(strategy='forward', threshold=10000)

        await stage.initialize(pipeline_config)

        query = text_query("hello")
        query.pipeline_config = pipeline_config
        query.resp_message_chain = [
            platform_message.MessageChain([platform_message.Plain(text="short response")])
        ]

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        assert len(result.new_query.resp_message_chain) == 1
        components = list(result.new_query.resp_message_chain[0])
        assert len(components) == 1
        assert isinstance(components[0], platform_message.Plain)
        assert components[0].text == 'short response'

    @pytest.mark.asyncio
    async def test_non_plain_component_skips(self):
        """resp_message_chain with non-Plain components should skip processing."""
        longtext = get_longtext_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        pipeline_config = make_longtext_config(strategy='forward', threshold=10)  # Low threshold

        await stage.initialize(pipeline_config)

        query = text_query("hello")
        query.pipeline_config = pipeline_config
        # Non-Plain component (Image)
        query.resp_message_chain = [
            platform_message.MessageChain([
                platform_message.Plain(text="short"),
                platform_message.Image(url="https://example.com/img.png")
            ])
        ]

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        components = list(result.new_query.resp_message_chain[0])
        assert [type(component) for component in components] == [
            platform_message.Plain,
            platform_message.Image,
        ]
        assert components[0].text == 'short'
        assert components[1].url == 'https://example.com/img.png'

    @pytest.mark.asyncio
    async def test_empty_resp_message_chain(self):
        """Empty resp_message_chain should be handled gracefully."""
        longtext = get_longtext_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        pipeline_config = make_longtext_config(strategy='forward')

        await stage.initialize(pipeline_config)

        query = text_query("hello")
        query.pipeline_config = pipeline_config
        query.resp_message_chain = []

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        assert result.new_query is query

    @pytest.mark.asyncio
    async def test_empty_response_message_chain_does_not_call_strategy(self):
        """Empty response chains should be a no-op for long text processing."""
        longtext = get_longtext_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)
        stage.strategy_impl = AsyncMock()

        query = text_query("hello")
        query.pipeline_config = make_longtext_config(strategy='forward', threshold=1)
        query.resp_message_chain = []

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        assert result.new_query is query
        stage.strategy_impl.process.assert_not_called()

class TestForwardStrategy:
    """Tests for ForwardComponentStrategy."""

    @pytest.mark.asyncio
    async def test_forward_strategy_processes(self):
        """ForwardComponentStrategy should create Forward component."""
        longtext = get_longtext_module()
        get_strategy_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        # Low threshold to trigger
        pipeline_config = make_longtext_config(strategy='forward', threshold=10)

        await stage.initialize(pipeline_config)

        query = text_query("hello")
        query.pipeline_config = pipeline_config
        # Create a mock adapter with bot_account_id
        mock_adapter = Mock()
        mock_adapter.bot_account_id = '12345'
        query.adapter = mock_adapter

        # Long text exceeding threshold
        long_text = "This is a very long response that exceeds the threshold"
        query.resp_message_chain = [
            platform_message.MessageChain([platform_message.Plain(text=long_text)])
        ]

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        components = list(result.new_query.resp_message_chain[0])
        assert len(components) == 1
        assert isinstance(components[0], platform_message.Forward)

    @pytest.mark.asyncio
    async def test_forward_strategy_direct_process(self):
        """Test ForwardComponentStrategy process method directly."""
        strategy = get_strategy_module()

        app = FakeApp()

        # Get ForwardComponentStrategy from preregistered
        for strat_cls in strategy.preregistered_strategies:
            if strat_cls.name == 'forward':
                strat = strat_cls(app)
                break
        else:
            pytest.skip('ForwardComponentStrategy not registered')

        await strat.initialize()

        query = text_query("hello")
        query.pipeline_config = make_longtext_config()
        mock_adapter = Mock()
        mock_adapter.bot_account_id = '12345'
        query.adapter = mock_adapter

        components = await strat.process("test message", query)

        assert len(components) == 1
        assert isinstance(components[0], platform_message.Forward)


class TestLongTextThreshold:
    """Tests for threshold boundary handling."""

    @pytest.mark.asyncio
    async def test_below_threshold_not_processed(self):
        """Text below threshold should not be transformed."""
        longtext = get_longtext_module()
        entities = get_entities_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        threshold = 100
        pipeline_config = make_longtext_config(strategy='forward', threshold=threshold)

        await stage.initialize(pipeline_config)

        query = text_query("hello")
        query.pipeline_config = pipeline_config

        # Text below threshold
        short_text = "x" * (threshold - 1)
        query.resp_message_chain = [
            platform_message.MessageChain([platform_message.Plain(text=short_text)])
        ]

        result = await stage.process(query, 'LongTextProcessStage')

        assert result.result_type == entities.ResultType.CONTINUE
        components = list(result.new_query.resp_message_chain[0])
        assert len(components) == 1
        assert isinstance(components[0], platform_message.Plain)
        assert components[0].text == short_text


class TestLongTextProcessStageImageStrategy:
    """Tests for image strategy handling (requires PIL/font)."""

    @pytest.mark.asyncio
    async def test_image_strategy_missing_font_fallback(self):
        """Missing font should fallback to forward strategy."""
        longtext = get_longtext_module()
        strategy = get_strategy_module()

        app = FakeApp()
        stage = longtext.LongTextProcessStage(app)

        # Use non-existent font path
        pipeline_config = make_longtext_config(strategy='image')

        # On non-Windows without font, should fallback to forward
        await stage.initialize(pipeline_config)

        # Should have initialized (possibly with fallback strategy)
        if stage.strategy_impl is not None:
            assert isinstance(stage.strategy_impl, strategy.LongTextStrategy)