#!/usr/bin/env python3
# Copyright (c) 2026 Lark Technologies Pte. Ltd.
# SPDX-License-Identifier: MIT

from __future__ import annotations

import json
import re
import sys
import xml.etree.ElementTree as ET
from difflib import SequenceMatcher
from pathlib import Path
from typing import Any


class XmlTextOverlapLintError(Exception):
    pass


def fail(message: str) -> None:
    raise XmlTextOverlapLintError(message)


def read_file(file_path: str | Path) -> str:
    return Path(file_path).read_text(encoding="utf-8")


def parse_args(argv: list[str]) -> dict[str, Any]:
    options: dict[str, Any] = {}
    index = 0
    while index < len(argv):
        token = argv[index]
        if not token.startswith("--"):
            fail(f"unexpected argument: {token}")
        key = token[2:]
        next_token = argv[index + 1] if index + 1 < len(argv) else None
        if next_token is None or next_token.startswith("--"):
            options[key] = True
            index += 1
            continue
        options[key] = next_token
        index += 2
    return options


def extract_attribute(tag_source: str, name: str) -> str | None:
    match = re.search(fr'{re.escape(name)}="([^"]+)"', tag_source)
    return match.group(1) if match else None


def extract_numeric_attribute(tag_source: str, name: str) -> int | float | None:
    raw = extract_attribute(tag_source, name)
    if raw is None:
        return None
    try:
        value = float(raw)
    except ValueError:
        return None
    return int(value) if value.is_integer() else value


def strip_xml(value: str) -> str:
    stripped = re.sub(r"<!\[CDATA\[([\s\S]*?)\]\]>", r"\1", value)
    stripped = re.sub(r"<[^>]+>", " ", stripped)
    stripped = stripped.replace("&nbsp;", " ")
    stripped = stripped.replace("&amp;", "&")
    stripped = stripped.replace("&lt;", "<")
    stripped = stripped.replace("&gt;", ">")
    stripped = stripped.replace("&quot;", '"')
    stripped = stripped.replace("&#39;", "'")
    return re.sub(r"\s+", " ", stripped).strip()


def xml_local_name(tag: str) -> str:
    return tag.rsplit("}", 1)[-1] if tag.startswith("{") else tag


def extract_error_context(xml: str, line: int | None, column: int | None, radius: int = 40) -> str | None:
    if line is None or column is None:
        return None
    lines = xml.splitlines()
    if line < 1 or line > len(lines):
        return None
    source_line = lines[line - 1]
    start = max(column - radius, 0)
    end = min(column + radius, len(source_line))
    return source_line[start:end].strip()


def build_xml_error_issue(error: ET.ParseError, xml: str) -> dict[str, Any]:
    line, column = getattr(error, "position", (None, None))
    return {
        "level": "error",
        "code": "xml_not_well_formed",
        "message": f"XML is not well-formed: {error}",
        "line": line,
        "column": column,
        "context": extract_error_context(xml, line, column),
        "hint": (
            "Escape raw user text before placing it in XML. In text nodes and attribute values, bare & must be "
            "written as &amp;. In text nodes, write < as &lt; and > as &gt;. For attribute URLs, use a=1&amp;b=2."
        ),
    }


def validate_xml_well_formed(xml: str) -> dict[str, Any] | None:
    try:
        root = ET.fromstring(xml)
    except ET.ParseError as error:
        return build_xml_error_issue(error, xml)

    root_name = xml_local_name(root.tag)
    if root_name not in {"presentation", "slide"}:
        fail("input must contain a <presentation> or <slide> root")
    return None


def parse_presentation(xml: str) -> dict[str, Any]:
    presentation_match = re.search(r"<presentation\b([^>]*)>", xml)
    if presentation_match:
        return {
            "width": int(float(extract_attribute(presentation_match.group(1), "width") or 960)),
            "height": int(float(extract_attribute(presentation_match.group(1), "height") or 540)),
            "slides": re.findall(r"<slide\b[\s\S]*?</slide>", xml),
        }
    slide_match = re.findall(r"<slide\b[\s\S]*?</slide>", xml)
    if slide_match:
        return {"width": 960, "height": 540, "slides": slide_match}
    fail("input must contain a <presentation> or <slide> root")


def extract_elements(slide_xml: str) -> list[dict[str, Any]]:
    elements: list[dict[str, Any]] = []
    for match in re.finditer(r"<shape\b([^>]*)>([\s\S]*?)</shape>", slide_xml):
        attrs, content = match.group(1), match.group(2)
        x = extract_numeric_attribute(attrs, "topLeftX")
        y = extract_numeric_attribute(attrs, "topLeftY")
        width = extract_numeric_attribute(attrs, "width")
        height = extract_numeric_attribute(attrs, "height")
        if all(value is not None for value in [x, y, width, height]):
            font_size = float(extract_attribute(content, "fontSize") or extract_attribute(attrs, "fontSize") or 16)
            elements.append(
                {
                    "id": f"shape-{len(elements) + 1}",
                    "kind": "shape",
                    "type": extract_attribute(attrs, "type") or "shape",
                    "textType": extract_attribute(content, "textType"),
                    "x": x,
                    "y": y,
                    "width": width,
                    "height": height,
                    "fontSize": font_size,
                    "text": strip_xml(content),
                }
            )

    for match in re.finditer(r"<(img|table|chart)\b([^>]*)/?>", slide_xml):
        attrs = match.group(2)
        x = extract_numeric_attribute(attrs, "topLeftX")
        y = extract_numeric_attribute(attrs, "topLeftY")
        width = extract_numeric_attribute(attrs, "width")
        height = extract_numeric_attribute(attrs, "height")
        if all(value is not None for value in [x, y, width, height]):
            elements.append(
                {
                    "id": f"{match.group(1)}-{len(elements) + 1}",
                    "kind": match.group(1),
                    "type": match.group(1),
                    "x": x,
                    "y": y,
                    "width": width,
                    "height": height,
                }
            )
    return elements


def intersects(left: dict[str, Any], right: dict[str, Any]) -> bool:
    return (
        left["x"] < right["x"] + right["width"]
        and left["x"] + left["width"] > right["x"]
        and left["y"] < right["y"] + right["height"]
        and left["y"] + left["height"] > right["y"]
    )


def is_text_element(element: dict[str, Any]) -> bool:
    return element["kind"] == "shape" and element["type"] == "text"


def has_text_content(element: dict[str, Any]) -> bool:
    return bool(element.get("text"))


def is_decorative_text(element: dict[str, Any]) -> bool:
    text = element.get("text") or ""
    return bool(text) and re.search(r"[A-Za-z0-9\u4e00-\u9fff]", text) is None


def normalize_text_for_overlap(text: str) -> str:
    return re.sub(r"\s+", "", text)


def is_similar_text_overlay(left: dict[str, Any], right: dict[str, Any]) -> bool:
    left_text = normalize_text_for_overlap(left.get("text") or "")
    right_text = normalize_text_for_overlap(right.get("text") or "")
    if not left_text or not right_text:
        return False
    if left_text == right_text or left_text in right_text or right_text in left_text:
        return True
    return SequenceMatcher(None, left_text, right_text).ratio() >= 0.75


def estimate_text_line_count(element: dict[str, Any]) -> int:
    font_size = element["fontSize"] if isinstance(element["fontSize"], (int, float)) else 16
    chars_per_line = max(1, int(element["width"] // max(font_size * 0.55, 1)))
    paragraphs = [paragraph for paragraph in re.split(r"\n+", element["text"]) if paragraph]
    line_count = 0
    for paragraph in paragraphs:
        logical_length = max(len(paragraph), 1)
        line_count += max(1, -(-logical_length // chars_per_line))
    return max(line_count, 1)


def estimate_text_visual_bbox(element: dict[str, Any]) -> dict[str, int | float] | None:
    if not is_text_element(element) or not has_text_content(element) or is_decorative_text(element):
        return None

    font_size = element["fontSize"] if isinstance(element["fontSize"], (int, float)) else 16
    char_width = max(font_size * 0.55, 1)
    line_count = estimate_text_line_count(element)
    visual_width = min(element["width"], max(1, len(element["text"]) * char_width))
    visual_height = min(element["height"], max(1, line_count * font_size * 1.2))
    return {
        "x": element["x"],
        "y": element["y"],
        "width": visual_width,
        "height": visual_height,
    }


def intersection_area(left: dict[str, Any], right: dict[str, Any]) -> int | float:
    width = min(left["x"] + left["width"], right["x"] + right["width"]) - max(left["x"], right["x"])
    height = min(left["y"] + left["height"], right["y"] + right["height"]) - max(left["y"], right["y"])
    if width <= 0 or height <= 0:
        return 0
    return width * height


def is_template_text_stack(left: dict[str, Any], right: dict[str, Any]) -> bool:
    if not (is_text_element(left) and is_text_element(right)):
        return False
    if not (has_text_content(left) and has_text_content(right)):
        return True
    top, bottom = sorted([left, right], key=lambda element: element["y"])
    top_type = top.get("textType")
    bottom_type = bottom.get("textType")
    allowed_pairs = {
        ("title", "sub-headline"),
        ("title", None),
        ("headline", "headline"),
        ("headline", None),
    }
    if (top_type, bottom_type) not in allowed_pairs:
        return False
    same_column = abs(top["x"] - bottom["x"]) <= 4
    vertical_offset = bottom["y"] - top["y"]
    top_font_size = float(top.get("fontSize", 16))
    return same_column and vertical_offset >= top_font_size * 0.75


def should_flag_overlap(left: dict[str, Any], right: dict[str, Any]) -> bool:
    if is_text_element(left) and not has_text_content(left):
        return False
    if is_text_element(right) and not has_text_content(right):
        return False
    if is_template_text_stack(left, right):
        return False
    if is_text_element(left) and is_text_element(right):
        if is_similar_text_overlay(left, right):
            return False
        left_visual = estimate_text_visual_bbox(left)
        right_visual = estimate_text_visual_bbox(right)
        if left_visual is None or right_visual is None:
            return False
        overlap_area = intersection_area(left_visual, right_visual)
        if overlap_area <= 0:
            return False
        smaller_area = min(
            left_visual["width"] * left_visual["height"],
            right_visual["width"] * right_visual["height"],
        )
        return smaller_area > 0 and overlap_area / smaller_area >= 0.30
    return False


def lint_slide(slide_xml: str, slide_number: int) -> dict[str, Any]:
    elements = extract_elements(slide_xml)
    issues: list[dict[str, Any]] = []

    for index, left in enumerate(elements):
        for right in elements[index + 1 :]:
            if not intersects(left, right) or not should_flag_overlap(left, right):
                continue
            issues.append(
                {
                    "level": "error",
                    "code": "bbox_overlap",
                    "elements": [left["id"], right["id"]],
                    "message": f'{left["id"]} overlaps {right["id"]}',
                }
            )

    return {"slide_number": slide_number, "element_count": len(elements), "issues": issues}


def lint_xml(xml: str, source_path: str | None = None) -> dict[str, Any]:
    xml_error = validate_xml_well_formed(xml)
    if xml_error:
        return {
            "file": source_path,
            "slide_size": {"width": 960, "height": 540},
            "summary": {"slide_count": 0, "error_count": 1, "warning_count": 0},
            "issues": [xml_error],
            "slides": [],
        }

    presentation = parse_presentation(xml)
    slides = [
        lint_slide(slide_xml, index + 1)
        for index, slide_xml in enumerate(presentation["slides"])
    ]
    error_count = sum(1 for slide in slides for issue in slide["issues"] if issue["level"] == "error")
    warning_count = sum(1 for slide in slides for issue in slide["issues"] if issue["level"] == "warning")
    return {
        "file": source_path,
        "slide_size": {"width": presentation["width"], "height": presentation["height"]},
        "summary": {"slide_count": len(slides), "error_count": error_count, "warning_count": warning_count},
        "slides": slides,
    }


def print_usage() -> None:
    print("Usage:\n  python3 xml_text_overlap_lint.py --input <presentation.xml>", file=sys.stderr)


def run_cli(argv: list[str] | None = None) -> None:
    options = parse_args(argv or sys.argv[1:])
    if options.get("help") or options.get("--help"):
        print_usage()
        raise SystemExit(0)
    if not options.get("input"):
        print_usage()
        fail("--input is required")
    input_path = Path(options["input"]).resolve()
    result = lint_xml(read_file(input_path), str(input_path))
    print(json.dumps(result, ensure_ascii=False, indent=2))
    if result["summary"]["error_count"] > 0:
        raise SystemExit(1)


if __name__ == "__main__":
    try:
        run_cli()
    except XmlTextOverlapLintError as error:
        print(f"xml-text-overlap-lint error: {error}", file=sys.stderr)
        raise SystemExit(1) from error