"""הזרקת bookmarks רטרואקטיבית ל-DOCX שלא נוצרו ע"י ה-exporter.

כאשר משתמש מעלה `עריכה-v*.docx` שנערך ב-Word מחוץ למערכת, אין בו את ה-
bookmarks שאנו מצפים להם (block-alef ... block-yod-bet). השירות כאן
מזהה את תחילת כל בלוק לפי סימני הפתיחה העבריים (א., ב., ... יב.) ב-
הפסקאות הראשונות שלו, ומזריק bookmarkStart/bookmarkEnd בהתאם.

נעשה בצורה defensive — אם לא מצליחים לזהות בלוק, הוא פשוט לא יקבל
bookmark (`missing_blocks` בתוצאה). השרת אמור להתריע למשתמש.
"""

from __future__ import annotations

import logging
import re
import shutil
import zipfile
from io import BytesIO
from pathlib import Path

from lxml import etree

from legal_mcp.services.docx_reviser import (
    NSMAP,
    _load_docx_xml,
    _save_docx_xml,
    _w,
)

logger = logging.getLogger(__name__)

# ── Block identification ──────────────────────────────────────────

# The 12 blocks in order, with their Hebrew letter marker
BLOCK_ORDER = [
    ("block-alef",     "א"),
    ("block-bet",      "ב"),
    ("block-gimel",    "ג"),
    ("block-dalet",    "ד"),
    ("block-heh",      "ה"),
    ("block-vav",      "ו"),
    ("block-zayin",    "ז"),
    ("block-chet",     "ח"),
    ("block-tet",      "ט"),
    ("block-yod",      "י"),
    ("block-yod-alef", "יא"),
    ("block-yod-bet",  "יב"),
]

# Regex matching a paragraph that begins with a Hebrew block marker
# followed by '.', ')', ' ', or end-of-string. The marker must be followed
# either by whitespace/punctuation or end of text to avoid matching longer
# words that happen to start with these letters.
_BLOCK_MARKERS_BY_LETTER: dict[str, str] = {letter: name for name, letter in BLOCK_ORDER}

# Longer markers (יא, יב) first so regex matches them before falling back to 'י'
_MARKER_ALTERNATION = "|".join(
    re.escape(letter)
    for letter in sorted(_BLOCK_MARKERS_BY_LETTER, key=len, reverse=True)
)
_BLOCK_MARKER_RE = re.compile(
    rf"^\s*({_MARKER_ALTERNATION})\s*[\.\)\-]\s*"
)

# Secondary heuristic: Hebrew section headings that reliably mark the
# start of each block in the Daphna Tamir style (used when markers
# "א.", "ב." etc. are missing — common in user-edited Word files).
#
# Key observations from the 12-block schema:
#   block-alef:   "בפני: דפנה תמיר" or decision number page
#   block-bet:    "ערר מספר" line
#   block-gimel:  appellants vs respondents (parties)
#   block-dalet:  bold "החלטה" centered
#   block-heh:    "רקע" / "רקע עובדתי" / "פתח דבר"
#   block-vav:    "תכניות חלות" / "ההליך שבפנינו" / "ההליכים בפני"
#   block-zayin:  "תמצית טענות" / "טענות הצדדים"
#   block-chet:   "תגובת המשיבה" / "עמדת הוועדה"
#   block-tet:    "ההליכים בפני ועדת הערר" / "הדיון בפנינו"
#   block-yod:    "דיון והכרעה" / "דיון"
#   block-yod-alef: "סוף דבר" / "סיכום"
#   block-yod-bet: "ההחלטה" (signature / closing block)
_BLOCK_HEADING_PATTERNS: list[tuple[str, list[str]]] = [
    ("block-alef", [r"בפני[:\s]", r"ועדת הערר"]),
    ("block-bet",  [r"^ערר\s+מספר", r"^ערר\s+\d"]),
    ("block-gimel", [r"^נגד\s*$", r"^—\s*נגד\s*—"]),
    ("block-dalet", [r"^החלטה\s*$"]),
    ("block-heh",  [r"^רקע\s*$", r"^רקע\s+עובדתי", r"^פתח\s+דבר"]),
    ("block-vav",  [
        r"^תכניות\s+חלות",
        r"^ההליכים?\s+שבפנינו",
        r"^ההליכים?\s+בפני\s+הוועדה\s+המקומית",
        r"^על\s+המקרקעין\s+חלות",
        r"^התכניות?\s+החלות",
        r"^במצב\s+התכנוני",
    ]),
    ("block-zayin", [
        r"^תמצית\s+טענות",
        r"^טענות\s+הצדדים",
        r"^טענות\s+העוררי",
        r"^טענות\s+העוררת",
    ]),
    ("block-chet", [
        r"^תגובת\s+המשיב",
        r"^עמדת\s+הוועדה\s+המקומית",
        r"^תשובת",
        r"^עיקר\s+תגובת\s+המשיב",
    ]),
    ("block-tet",  [
        r"^ההליכים?\s+בפני\s+ועדת\s+הערר",
        r"^הדיון\s+בפנינו",
        r"^הדיון\s+בוועדת\s+הערר",
    ]),
    ("block-yod",  [r"^דיון\s+והכרעה", r"^דיון\s*$", r"^ההכרעה"]),
    ("block-yod-alef", [r"^סוף\s+דבר", r"^סיכום\s*$"]),
    # block-yod-bet "על כן" must be operative — paired with אנו/הערר/הוועדה.
    # Loose `^על כן` alone matches mid-discussion transitions ("על כן, במקום בו...")
    # and steals the bookmark from block-yod-alef via forward-scan.
    ("block-yod-bet", [
        r"^ההחלטה\s*$",
        r"^על\s+כן[,\.\s]+(?:אנו|הערר|הוועדה|ועדת\s+הערר)\b",
    ]),
]

_COMPILED_HEADING_PATTERNS: list[tuple[str, list[re.Pattern[str]]]] = [
    (name, [re.compile(p) for p in patterns])
    for name, patterns in _BLOCK_HEADING_PATTERNS
]


def _paragraph_text(p: etree._Element) -> str:
    """Return the full text of a paragraph, joining all w:t nodes."""
    return "".join(p.itertext()).strip()


def _detect_block_starts(
    paragraphs: list[etree._Element],
) -> dict[str, int]:
    """Return a mapping of block_name → paragraph index (start of that block).

    Uses a greedy scan: for each paragraph, if its text starts with an
    expected block marker and the block hasn't been assigned yet, assign
    this paragraph as the block's start.
    """
    found: dict[str, int] = {}
    expected_order = [name for name, _ in BLOCK_ORDER]
    pointer = 0  # index into expected_order — next expected block

    for i, p in enumerate(paragraphs):
        text = _paragraph_text(p)
        if not text:
            continue

        matched_name: str | None = None

        # Try marker-based (א., ב., ...) first
        m = _BLOCK_MARKER_RE.match(text)
        if m:
            letter = m.group(1)
            matched_name = _BLOCK_MARKERS_BY_LETTER.get(letter)

        # Fall back to heading-keyword heuristic (Daphna style)
        if matched_name is None:
            for name, patterns in _COMPILED_HEADING_PATTERNS:
                if name in found:
                    continue
                # Only check patterns for blocks we haven't assigned yet
                # AND that come at/after the current pointer — to keep the
                # greedy forward-scan semantics consistent with markers.
                if expected_order.index(name) < pointer:
                    continue
                if any(pat.search(text) for pat in patterns):
                    matched_name = name
                    break

        if matched_name is None:
            continue
        if matched_name in found:
            continue
        if pointer >= len(expected_order):
            continue
        name_idx_in_order = expected_order.index(matched_name)
        if name_idx_in_order >= pointer:
            found[matched_name] = i
            pointer = name_idx_in_order + 1
    return found


def _insert_bookmark_around_range(
    body: etree._Element,
    paragraphs: list[etree._Element],
    start_idx: int,
    end_idx: int,
    name: str,
    bm_id: int,
) -> None:
    """Insert bookmarkStart at the start of paragraph start_idx and
    bookmarkEnd at the end of paragraph end_idx."""
    start_el = etree.Element(_w("bookmarkStart"))
    start_el.set(_w("id"), str(bm_id))
    start_el.set(_w("name"), name)

    end_el = etree.Element(_w("bookmarkEnd"))
    end_el.set(_w("id"), str(bm_id))

    start_p = paragraphs[start_idx]
    end_p = paragraphs[end_idx]
    start_p.insert(0, start_el)
    end_p.append(end_el)


def _next_bookmark_id(doc_tree: etree._Element) -> int:
    """Find max existing bookmark id and return next unused."""
    max_id = 9999
    for el in doc_tree.iterfind(".//w:bookmarkStart", NSMAP):
        wid = el.get(_w("id"))
        if wid:
            try:
                max_id = max(max_id, int(wid))
            except ValueError:
                pass
    return max_id + 1


# ── Public API ────────────────────────────────────────────────────


def retrofit_bookmarks(
    docx_path: str | Path,
    *,
    output_path: str | Path | None = None,
    backup: bool = True,
) -> dict:
    """Inject block-* bookmarks into an existing DOCX via heuristic detection.

    Args:
        docx_path: path to DOCX file (modified in place unless output_path set).
        output_path: if given, write to this path instead of overwriting.
        backup: if True and writing in place, save the original as
                `<path>.pre-retrofit.docx` first.

    Returns:
        {
          'bookmarks_added': ['block-alef', ...],
          'missing_blocks':  ['block-dalet', ...],
          'existing_bookmarks': [...]   # bookmarks already on the doc
        }
    """
    docx_path = Path(docx_path)
    if not docx_path.exists():
        raise FileNotFoundError(str(docx_path))

    if output_path is None:
        output_path = docx_path
    output_path = Path(output_path)

    members, doc_tree, settings_tree = _load_docx_xml(docx_path)

    # Existing bookmarks
    existing_names: list[str] = []
    for el in doc_tree.iterfind(".//w:bookmarkStart", NSMAP):
        name = el.get(_w("name"))
        if name:
            existing_names.append(name)

    # Collect *top-level* body paragraphs (don't descend into tables etc.
    # for now — MVP). The XPath ".//w:p" would include table cells too;
    # for retrofitting we only care about the main flow.
    body = doc_tree.find(f".//{_w('body')}")
    if body is None:
        raise ValueError("document has no <w:body>")
    paragraphs = [p for p in body if p.tag == _w("p")]

    if not paragraphs:
        return {
            "bookmarks_added": [],
            "missing_blocks": [n for n, _ in BLOCK_ORDER],
            "existing_bookmarks": existing_names,
        }

    block_starts = _detect_block_starts(paragraphs)

    # Cover-block fallback: alef/bet/gimel/dalet are template metadata
    # (judges, case number, parties, "החלטה" title) that don't appear in
    # the body of user-edited DOCX files — they live in headers/template.
    # Inject zero-content anchors at paragraph 0 so apply_user_edit can
    # still target them later.
    structural_fallback: list[str] = []
    cover_blocks = ["block-alef", "block-bet", "block-gimel", "block-dalet"]
    first_detected_idx = min(block_starts.values()) if block_starts else 0
    for i, name in enumerate(cover_blocks):
        if name not in block_starts:
            idx = min(i, max(0, first_detected_idx - 1))
            block_starts[name] = idx
            structural_fallback.append(name)

    # Calculate end_idx for each block = paragraph before the next block's start,
    # or last paragraph if this is the last block found.
    ordered_found = sorted(block_starts.items(), key=lambda kv: kv[1])
    ranges: list[tuple[str, int, int]] = []
    for i, (name, start_idx) in enumerate(ordered_found):
        if i + 1 < len(ordered_found):
            end_idx = ordered_found[i + 1][1] - 1
        else:
            end_idx = len(paragraphs) - 1
        ranges.append((name, start_idx, max(start_idx, end_idx)))

    # Backup if overwriting in place
    if backup and output_path.resolve() == docx_path.resolve():
        backup_path = docx_path.with_suffix(".pre-retrofit.docx")
        shutil.copy2(str(docx_path), str(backup_path))

    # Inject bookmarks, skipping any that already exist
    next_id = _next_bookmark_id(doc_tree)
    added: list[str] = []
    for name, s, e in ranges:
        if name in existing_names:
            continue
        _insert_bookmark_around_range(body, paragraphs, s, e, name, next_id)
        added.append(name)
        next_id += 1

    _save_docx_xml(members, doc_tree, settings_tree, output_path)

    missing = [
        n for n, _ in BLOCK_ORDER
        if n not in block_starts
        and n not in existing_names
    ]
    logger.info("retrofit %s: added=%s missing=%s structural=%s",
                docx_path.name, added, missing, structural_fallback)
    return {
        "bookmarks_added": added,
        "missing_blocks": missing,
        "structural_fallback": structural_fallback,
        "existing_bookmarks": existing_names,
    }