"""Split and filter coaching narrative text for the web UI."""

from __future__ import annotations

from chess_tutor.cohort.opening_families import bucket_display_name
from chess_tutor.web.sections import (
    NarrativeBlockId,
    narrative_block_skipped,
    section_enabled,
    WebSectionId,
)

_OPENING_BUCKET_TITLES = frozenset(
    bucket_display_name(bucket)
    for bucket in ("white", "black_vs_e4", "black_vs_d4", "black_vs_c4", "other")
) | {"Other"}

_WEB_NARRATIVE_SKIP_TITLES = frozenset(
    {"Opening patterns", "Top opening positions", "Puzzle practice"}
)

_TOP_LEVEL_NARRATIVE_HEADERS = frozenset(
    {
        "Story for this player",
        "Your focus this week",
        "This week's checklist",
        "Examples from your games",
        "Opening patterns",
        "Top opening positions",
        "Practice plan",
        "Puzzle practice",
    }
)


def _is_top_level_narrative_header(line: str, stripped: str) -> bool:
    if not stripped or line.startswith((" ", "\t")) or stripped.startswith("-"):
        return False
    return stripped.rstrip(":") in _TOP_LEVEL_NARRATIVE_HEADERS


def _strip_web_duplicate_sections(narrative: str) -> str:
    """Remove opening/puzzle blocks when dedicated UI cards show them."""
    skip_titles: set[str] = set()
    if section_enabled(WebSectionId.OPENINGS) and narrative_block_skipped(
        NarrativeBlockId.OPENING_DUPLICATE
    ):
        skip_titles.add("Opening patterns")
        skip_titles.add("Top opening positions")
    if section_enabled(WebSectionId.PUZZLES) and narrative_block_skipped(
        NarrativeBlockId.PUZZLE_DUPLICATE
    ):
        skip_titles.add("Puzzle practice")
    if not skip_titles:
        return narrative.strip()

    lines = narrative.splitlines()
    result: list[str] = []
    skipping = False
    i = 0
    while i < len(lines):
        line = lines[i]
        stripped = line.strip()
        if stripped in skip_titles or stripped.rstrip(":") in skip_titles:
            skipping = True
            i += 1
            continue
        if skipping:
            if _is_top_level_narrative_header(line, stripped):
                skipping = False
            else:
                i += 1
                continue
        result.append(line)
        i += 1
    return "\n".join(result).strip()


def _looks_like_opening_section(section: dict[str, str]) -> bool:
    title = section["title"]
    body = section["body"]
    if title in _WEB_NARRATIVE_SKIP_TITLES or title in _OPENING_BUCKET_TITLES:
        return True
    if title.startswith("#") and " — " in title:
        return True
    return "You play:" in body and "Recommended:" in body


def _looks_like_puzzle_section(section: dict[str, str]) -> bool:
    title = section["title"]
    body = section["body"]
    if title in _WEB_NARRATIVE_SKIP_TITLES:
        return True
    if "Rated ladder" in title or "Rated ladder" in body:
        return True
    if "lichess.org/training/" in body:
        return True
    if "Themes:" in body and " Elo (" in body:
        return True
    return False


def _looks_like_coaching_report_section(section: dict[str, str]) -> bool:
    title = section["title"].strip()
    if title in {"Coaching report", "Story for this player"}:
        return True
    return section["body"].strip().startswith("Story for this player")


def _looks_like_cohort_tendency_section(section: dict[str, str]) -> bool:
    title = section["title"].strip().rstrip(":")
    return title.startswith("Compared to others at your rating")


_NARRATIVE_BLOCK_MATCHERS: dict[NarrativeBlockId, object] = {
    NarrativeBlockId.COACHING_REPORT: _looks_like_coaching_report_section,
    NarrativeBlockId.COHORT_TENDENCY: _looks_like_cohort_tendency_section,
    NarrativeBlockId.OPENING_DUPLICATE: _looks_like_opening_section,
    NarrativeBlockId.PUZZLE_DUPLICATE: _looks_like_puzzle_section,
}

_CLIMBER_SECTION_PREFIX = "Players who climbed from your bracket toward"


def _web_friendly_narrative_title(title: str) -> str:
    stripped = title.strip().rstrip(":")
    if stripped.startswith(_CLIMBER_SECTION_PREFIX):
        return "Playstyle changes (from similar climbers)"
    if stripped == "Practical emphasis (by priority)":
        return "Recommended playstyle changes"
    return title


def _should_skip_narrative_section(
    section: dict[str, str],
    *,
    filters: tuple | None = None,
) -> bool:
    for block_id, matcher in _NARRATIVE_BLOCK_MATCHERS.items():
        if narrative_block_skipped(block_id, filters=filters) and matcher(section):
            return True
    return False


def _split_narrative_sections(narrative: str) -> list[dict[str, str]]:
    """Split coaching narrative into titled sections."""
    text = narrative.strip()
    if not text:
        return []

    sections: list[dict[str, str]] = []
    current_title = "Coaching report"
    current_lines: list[str] = []

    for line in text.splitlines():
        stripped = line.strip()
        if not stripped and not current_lines:
            continue
        if (
            stripped
            and not stripped.startswith("-")
            and not line.startswith("  ")
            and not line.startswith("\t")
            and stripped.endswith(":")
            and len(stripped) < 80
        ):
            if current_lines:
                sections.append(
                    {
                        "title": current_title,
                        "body": "\n".join(current_lines).strip(),
                    }
                )
            current_title = stripped.rstrip(":")
            current_lines = []
            continue
        current_lines.append(line.rstrip())

    if current_lines:
        sections.append(
            {
                "title": current_title,
                "body": "\n".join(current_lines).strip(),
            }
        )
    return sections


def build_web_narrative_sections(
    narrative: str,
    *,
    narrative_filters: tuple | None = None,
) -> list[dict[str, str]]:
    """Narrative blocks for the web UI, respecting section registry filters."""
    if not section_enabled(WebSectionId.NARRATIVE):
        return []

    cleaned = _strip_web_duplicate_sections(narrative)
    sections: list[dict[str, str]] = []
    for section in _split_narrative_sections(cleaned):
        if _should_skip_narrative_section(section, filters=narrative_filters):
            continue
        sections.append(
            {
                "title": _web_friendly_narrative_title(section["title"]),
                "body": section["body"],
            }
        )
    return sections