"""Unified conversion planner.

Pure functions that take a ConversionRequest and produce a ConversionPlan.
No side effects, no I/O — all complexity from both UIs in one place.

This is Stage 2 of the conversion flow unification plan.
"""

from __future__ import annotations

from pathlib import Path
from typing import Any, Dict, List, Optional, Tuple

from abogen.application.conversion_models import (
    ChapterPlan,
    ConversionPlan,
    IntroOutroSpec,
    OutputLayout,
    SegmentPlan,
)
from abogen.application.conversion_request import ConversionRequest
from abogen.application.output_layout_service import resolve_output_layout
from abogen.domain.chapter_overrides import apply_chapter_overrides
from abogen.domain.file_type import auto_select_relevant_chapters
from abogen.domain.intro_outro import resolve_intro, resolve_outro
from abogen.domain.metadata_extraction import extract_metadata_for_file
from abogen.domain.metadata_merge import merge_metadata
from abogen.subtitle_utils import split_text_by_voice_markers


def build_conversion_plan(request: ConversionRequest) -> ConversionPlan:
    """Build a complete conversion plan from a request.

    This is the single entry point that both UIs will call.
    It handles all the planning logic that was previously duplicated
    in both PyQt and WebUI conversion runners.

    Args:
        request: Normalized conversion request

    Returns:
        ConversionPlan with all chapters, segments, and output layout

    Raises:
        ValueError: If request is invalid (no source, no chapters, etc.)
    """
    # 1. Extract and validate source
    source_text = _extract_source_text(request)
    if not source_text or not source_text.strip():
        raise ValueError("No text content to convert")

    # 2. Extract metadata
    metadata, extraction = _extract_metadata(request)

    # 3. Parse chapters
    raw_chapters = _parse_chapters(source_text, request)

    # 4. Apply chapter selection/overrides
    selected_chapters = _apply_selection(raw_chapters, request)

    # 5. Build segments for each chapter
    chapters = _build_chapters(selected_chapters, request)

    # 6. Build intro/outro
    intro, outro = _build_intro_outro(metadata, request)

    # 7. Resolve output layout
    output_layout = resolve_output_layout(request)

    return ConversionPlan(
        request=request,
        metadata=metadata,
        chapters=chapters,
        intro=intro,
        outro=outro,
        output_layout=output_layout,
        extraction=extraction,
    )


def _extract_source_text(request: ConversionRequest) -> Optional[str]:
    """Extract text from request source."""
    from abogen.subtitle_utils import clean_text

    if request.direct_text:
        text = clean_text(request.direct_text)
    elif request.source_path and request.source_path.exists():
        encoding = "utf-8"
        try:
            with open(request.source_path, "r", encoding=encoding, errors="replace") as f:
                text = f.read()
        except Exception:
            return None
        text = clean_text(text)
    else:
        return None

    # Apply word substitutions if configured
    if request.word_substitution:
        from abogen.word_substitution import apply_word_substitutions

        ws = request.word_substitution
        text = apply_word_substitutions(
            text,
            ws.substitutions_list,
            ws.case_sensitive,
            ws.replace_caps,
            ws.replace_numerals,
            ws.fix_punctuation,
        )

    return text


def _extract_metadata(
    request: ConversionRequest,
) -> Tuple[Dict[str, Any], Optional[Any]]:
    """Extract metadata from source file.

    Returns (metadata, extraction) tuple.
    """
    if request.direct_text:
        return dict(request.metadata_tags), None

    if request.source_path and request.source_path.exists():
        try:
            extraction = extract_metadata_for_file(
                str(request.source_path), is_direct_text=False
            )
            metadata = dict(extraction.metadata) if extraction.metadata else {}
        except Exception:
            extraction = None
            metadata = {}
        metadata = merge_metadata(metadata, request.metadata_tags)
        return metadata, extraction

    return dict(request.metadata_tags), None


def _parse_chapters(
    source_text: str, request: ConversionRequest
) -> List[Tuple[str, str, str]]:
    """Parse source text into raw chapters.

    Returns list of (title, body_text, default_voice) tuples.
    """
    from abogen.domain.text_chapters import parse_chapters_from_text

    # Text is already cleaned in _extract_source_text, so clean=False here
    chapters = parse_chapters_from_text(source_text, default_title="text", clean=False)

    # Default voice from request
    default_voice = request.voice or "M1"

    return [(title, text, default_voice) for title, text in chapters]


def _apply_selection(
    raw_chapters: List[Tuple[str, str, str]], request: ConversionRequest
) -> List[Tuple[str, str, str]]:
    """Apply chapter selection and overrides."""
    from abogen.text_extractor import ExtractedChapter

    # Convert to ExtractedChapter objects for auto_select_relevant_chapters
    extracted = [
        ExtractedChapter(title=title, text=text)
        for title, text, _ in raw_chapters
    ]

    # If user specified chapters, apply overrides
    chapter_chunk = request.chapter_chunk
    if chapter_chunk and chapter_chunk.chapter_overrides:
        selected, _, diagnostics = apply_chapter_overrides(extracted, chapter_chunk.chapter_overrides)
        if selected:
            # Map back to (title, text, voice) tuples
            result = []
            for ch in selected:
                # Find matching original chapter to get voice
                voice = request.voice or "M1"
                for orig_title, orig_text, orig_voice in raw_chapters:
                    if orig_title == ch.title:
                        voice = orig_voice
                        break
                result.append((ch.title, ch.text or "", voice))
            return result
        # If no chapters selected, fall through to auto-selection

    # Auto-select relevant chapters
    from abogen.domain.file_type import infer_file_type

    file_type = infer_file_type(request.source_path) if request.source_path else "text"
    result = auto_select_relevant_chapters(extracted, file_type)
    filtered = result.kept

    if filtered:
        # Map back to (title, text, voice) tuples
        result = []
        for ch in filtered:
            voice = request.voice or "M1"
            for orig_title, orig_text, orig_voice in raw_chapters:
                if orig_title == ch.title:
                    voice = orig_voice
                    break
            result.append((ch.title, ch.text or "", voice))
        return result

    # Fall back to all chapters
    return raw_chapters


def _build_chapters(
    selected_chapters: List[Tuple[str, str, str]], request: ConversionRequest
) -> List[ChapterPlan]:
    """Build ChapterPlan with SegmentPlan for each chapter."""
    chapters = []

    for idx, (title, body_text, default_voice) in enumerate(selected_chapters, 1):
        # Build segments for this chapter
        segments = _build_segments(body_text, default_voice, request)

        chapter = ChapterPlan(
            index=idx,
            title=title,
            original_title=title,
            body_text=body_text,
            segments=segments,
            voice_spec=default_voice,
        )
        chapters.append(chapter)

    return chapters


def _build_segments(
    body_text: str, default_voice: str, request: ConversionRequest
) -> List[SegmentPlan]:
    """Build SegmentPlan list for a chapter's body text.

    Handles voice markers (PyQt) and chunks (WebUI).
    """
    segments = []

    # Check for chunks (WebUI style)
    chapter_chunk = request.chapter_chunk
    if chapter_chunk and chapter_chunk.chunks:
        # Group chunks by chapter (simplified — assume chunks are for current chapter)
        for chunk_idx, chunk in enumerate(chapter_chunk.chunks):
            chunk_text = chunk.get("normalized_text") or chunk.get("text", "")
            if not chunk_text or not chunk_text.strip():
                continue

            chunk_voice = _resolve_chunk_voice(chunk, default_voice, request)
            speaker_id = chunk.get("speaker_id", "narrator")

            segments.append(
                SegmentPlan(
                    text=chunk_text.strip(),
                    voice_spec=chunk_voice,
                    kind="body",
                    speaker_id=speaker_id,
                    chunk_id=chunk.get("id"),
                    chunk_index=chunk.get("chunk_index", chunk_idx),
                    level=chunk.get("level", chapter_chunk.chunk_level),
                    source="chunk",
                )
            )
        return segments

    # Check for voice markers (PyQt style)
    # Detect markers even if validation fails (voice names may not be loaded yet)
    from abogen.subtitle_utils import _VOICE_MARKER_SEARCH_PATTERN

    has_voice_markers = bool(_VOICE_MARKER_SEARCH_PATTERN.search(body_text))
    voice_segments, last_voice, valid_count, invalid_count = split_text_by_voice_markers(
        body_text, default_voice
    )

    if has_voice_markers or (len(voice_segments) > 1):
        # Voice markers were used
        for voice_name, segment_text in voice_segments:
            if not segment_text or not segment_text.strip():
                continue
            segments.append(
                SegmentPlan(
                    text=segment_text.strip(),
                    voice_spec=voice_name,
                    kind="body",
                    source="voice_marker",
                )
            )
        return segments

    # No voice markers — single segment for entire body
    if body_text and body_text.strip():
        segments.append(
            SegmentPlan(
                text=body_text.strip(),
                voice_spec=default_voice,
                kind="body",
                source="chapter",
            )
        )

    return segments


def _resolve_chunk_voice(
    chunk: Dict[str, Any], default_voice: str, request: ConversionRequest
) -> str:
    """Resolve voice for a chunk."""
    # Check for speaker-based voice
    speaker_id = chunk.get("speaker_id", "narrator")
    speakers = request.chapter_chunk.speakers if request.chapter_chunk else {}
    if speaker_id and speaker_id != "narrator" and speakers:
        speaker_config = speakers.get(speaker_id, {})
        if isinstance(speaker_config, dict):
            voice = speaker_config.get("voice")
            if voice:
                return voice

    # Check for direct voice field
    voice = chunk.get("voice")
    if voice:
        return voice

    return default_voice


def _build_intro_outro(
    metadata: Dict[str, Any], request: ConversionRequest
) -> Tuple[Optional[IntroOutroSpec], Optional[IntroOutroSpec]]:
    """Build intro and outro specs."""
    intro_spec = None
    outro_spec = None

    # Intro
    if request.read_title_intro:
        resolved = resolve_intro(
            metadata,
            request.original_filename,
            True,
            request.voice or "M1",
            request.voice or "M1",
            [],
        )
        if resolved.enabled:
            intro_spec = IntroOutroSpec(
                enabled=True,
                text=resolved.text,
                voice_spec=resolved.voice_spec,
                kind="intro",
            )

    # Outro
    if request.read_closing_outro:
        resolved = resolve_outro(
            metadata,
            request.original_filename,
            True,
            request.voice or "M1",
            request.voice or "M1",
            [],
        )
        if resolved.enabled:
            outro_spec = IntroOutroSpec(
                enabled=True,
                text=resolved.text,
                voice_spec=resolved.voice_spec,
                kind="outro",
            )

    return intro_spec, outro_spec


# Output layout resolution is now in application/output_layout_service.py