"""Utilities to render portfolio analysis output with styled HTML."""

from __future__ import annotations

import re
from html import escape
from html.parser import HTMLParser
from typing import Iterable, List, Tuple

_SPAN_TAG = re.compile(r"</?span(?:\s+[^>]*?)?>", re.IGNORECASE)
_SPAN_ATTR = re.compile(r"([a-zA-Z_:][-a-zA-Z0-9_:.]*)\s*=\s*\"(.*?)\"")

ALLOWED_CLASSES = {
    "analysis-container",
    "analysis-output",
    "analysis-status",
    "analysis-line",
    "analysis-keyword",
    "analysis-caret",
    "bullet",
    "metric",
    "metric-name",
    "metric-number",
    "metric-separator",
    "metric-value",
    "negative",
    "neutral",
    "positive",
    "section",
    "section-divider",
}

ALLOWED_TAGS = {"div", "p", "span", "h2", "h3", "ul", "ol", "li", "hr"}

SECTION_TITLES: Tuple[str, ...] = (
    "Objective Evaluation",
    "Risk Assessment",
    "Interpretation",
    "Recommendation",
)

KEYWORD_HIGHLIGHTS: Tuple[str, ...] = (
    "poor performance",
    "high risk",
    "underperformed",
    "volatility",
    "recommendation",
    "drawdown",
    "exposure",
    "opportunity",
)

METRIC_TOOLTIPS = {
    "Sharpe Ratio": "Sharpe Ratio: excess return per unit of total risk.",
    "Sortino Ratio": "Sortino Ratio: downside-risk-adjusted performance.",
    "Calmar Ratio": "Calmar Ratio: annual return divided by max drawdown.",
    "Max Drawdown": "Max Drawdown: largest observed portfolio loss from peak.",
    "Beta": "Beta: sensitivity to benchmark movements.",
    "Volatility": "Volatility: standard deviation of returns.",
}

_KEYWORD_REGEX = re.compile(
    "|".join(re.escape(word) for word in KEYWORD_HIGHLIGHTS), re.IGNORECASE
)
_METRIC_LINE = re.compile(r"^[-•]?\s*([^:]+?):\s*(.+)$")
_SECTION_HEADER = re.compile(r"^\*\*(.+?)\*\*")


def render_status_html(message: str) -> str:
    """Render interim status or error messages."""
    safe = escape(message)
    body = f"<div class='analysis-output'><p class='analysis-status'>{safe}</p></div>"
    return _wrap_with_container(body)


def render_analysis_html(text: str, show_caret: bool = False) -> str:
    """Convert LLM response into themed HTML without inline styles."""
    stripped = text.strip()
    if not stripped:
        html = _wrap_with_container("<div class='analysis-output'></div>")
        return _append_caret(html) if show_caret else html

    if _looks_like_html(stripped):
        sanitized = _sanitize_analysis_html(stripped)
        if sanitized.strip():
            cleaned = _trim_trailing_breaks(sanitized).strip()
            html = _wrap_with_container(cleaned)
            return _append_caret(html) if show_caret else html

    sections = _split_sections(stripped)
    if not sections:
        formatted_lines = _format_lines(stripped.splitlines())
        body = "".join(formatted_lines)
        html = _wrap_with_container(f"<div class='analysis-output'>{body}</div>")
        return _append_caret(html) if show_caret else html

    parts: List[str] = ["<div class='analysis-output'>"]
    for idx, (title, content) in enumerate(sections):
        parts.append("<div class='section'>")
        parts.append(f"<h2>{escape(title)}</h2>")
        formatted_lines = _format_lines(content.splitlines())
        parts.extend(formatted_lines)
        parts.append("</div>")
        if idx < len(sections) - 1:
            parts.append("<div class='section-divider'></div>")
    parts.append("</div>")
    html = "".join(parts)
    html = _wrap_with_container(_trim_trailing_breaks(html).strip())
    return _append_caret(html) if show_caret else html


def _split_sections(text: str) -> List[Tuple[str, str]]:
    sections: List[Tuple[str, str]] = []
    current_title = None
    buffer: List[str] = []

    allowed_headers = {title.lower(): title for title in SECTION_TITLES}

    for line in text.splitlines():
        stripped = line.strip()
        header_match = _SECTION_HEADER.match(stripped)
        if header_match:
            # flush previous section
            if current_title and buffer:
                sections.append((current_title, "\n".join(buffer).strip()))
                buffer.clear()
            matched_title = header_match.group(1).strip()
            normalized = allowed_headers.get(matched_title.lower(), matched_title)
            current_title = normalized
            continue
        if stripped in allowed_headers:
            if current_title and buffer:
                sections.append((current_title, "\n".join(buffer).strip()))
                buffer.clear()
            current_title = allowed_headers[stripped]
            continue
        buffer.append(line)

    if current_title and buffer:
        sections.append((current_title, "\n".join(buffer).strip()))
    return sections


def _format_lines(lines: Iterable[str]) -> List[str]:
    formatted: List[str] = []
    paragraph_buffer: List[str] = []
    seen_metrics: set[str] = set()
    seen_paragraphs: set[str] = set()

    def flush_paragraph() -> None:
        if not paragraph_buffer:
            return
        paragraph_text = " ".join(paragraph_buffer)
        normalized = re.sub(r"\s+", " ", paragraph_text).strip()
        lower_key = normalized.lower()
        if lower_key and lower_key not in seen_paragraphs:
            seen_paragraphs.add(lower_key)
            formatted.append(
                f"<p class='analysis-line'>{_decorate_text(paragraph_text)}</p>"
            )
        paragraph_buffer.clear()

    for raw_line in lines:
        line = raw_line.strip()
        if not line:
            flush_paragraph()
            continue

        metric_match = _METRIC_LINE.match(line)
        if metric_match:
            flush_paragraph()
            metric_name = metric_match.group(1).strip().lower()
            if metric_name and metric_name not in seen_metrics:
                seen_metrics.add(metric_name)
                formatted.append(
                    _format_metric_line(
                        metric_match.group(1), metric_match.group(2)
                    )
                )
            continue

        bullet = raw_line.lstrip().startswith(('-', '•'))
        if bullet:
            flush_paragraph()
            content = re.sub(r"^[-•]\s*", "", line)
            normalized = re.sub(r"\s+", " ", content).strip().lower()
            if normalized and normalized not in seen_paragraphs:
                seen_paragraphs.add(normalized)
                formatted.append(
                    f"<p class='analysis-line bullet'>{_decorate_text(content)}</p>"
                )
            continue

        paragraph_buffer.append(line)

    flush_paragraph()
    return formatted


def _format_metric_line(name: str, value: str) -> str:
    tooltip = METRIC_TOOLTIPS.get(name.strip())
    name_text = escape(name.strip())
    name_span = (
        f"<span class='metric-name' data-tooltip='{escape(tooltip)}'>{name_text}</span>"
        if tooltip
        else f"<span class='metric-name'>{name_text}</span>"
    )
    value_span = f"<span class='metric-value'>{_decorate_metric_value(value)}</span>"
    return (
        "<p class='analysis-line metric'>"
        f"{name_span} <span class='metric-separator'>:</span> {value_span}"
        "</p>"
    )


def _decorate_text(text: str) -> str:
    preserved = _preserve_spans(text)
    if not preserved:
        return ""
    highlighted = _KEYWORD_REGEX.sub(
        lambda match: f"<span class='analysis-keyword'>{match.group(0)}</span>", preserved
    )
    return highlighted


_NUMERIC_TOKEN = re.compile(r"[-+]?\d+(?:[\.,]\d+)?(?:\s?(?:%|bps|bp|x|X))?")


def _decorate_metric_value(value: str) -> str:
    parts: List[str] = []
    last_index = 0
    for match in _NUMERIC_TOKEN.finditer(value):
        start, end = match.span()
        if start > last_index:
            parts.append(_decorate_text(value[last_index:start]))
        token = match.group(0)
        number_class = _numeric_class(token)
        parts.append(
            f"<span class='metric-number {number_class}'>{escape(token.strip())}</span>"
        )
        last_index = end

    if last_index < len(value):
        parts.append(_decorate_text(value[last_index:]))

    if not parts:
        return _decorate_text(value)

    return "".join(parts)


def _preserve_spans(text: str) -> str:
    """Escape text while allowing limited span tags for inline emphasis."""

    result: List[str] = []
    last_index = 0
    for match in _SPAN_TAG.finditer(text):
        start, end = match.span()
        if start > last_index:
            result.append(escape(text[last_index:start]))
        result.append(_sanitize_span(match.group(0)))
        last_index = end
    if last_index < len(text):
        result.append(escape(text[last_index:]))
    return "".join(result)


def _sanitize_span(tag: str) -> str:
    if tag.startswith("</"):
        return "</span>"

    attributes = {}
    for attr, value in _SPAN_ATTR.findall(tag):
        if attr.lower() != "class":
            continue
        filtered = _filter_allowed_classes(value)
        if filtered:
            attributes["class"] = filtered

    attr_string = "".join(
        f" {name}=\"{escape(val)}\"" for name, val in attributes.items()
    )
    return f"<span{attr_string}>"


def _filter_allowed_classes(raw_value: str) -> str:
    classes = [cls for cls in raw_value.split() if cls in ALLOWED_CLASSES]
    return " ".join(dict.fromkeys(classes))


def _looks_like_html(text: str) -> bool:
    return bool(re.search(r"<\s*(div|p|span|h2|h3|ul|ol|li)\b", text, re.IGNORECASE))


class _AnalyzerHTMLSanitizer(HTMLParser):
    def __init__(self) -> None:
        super().__init__()
        self.parts: List[str] = []
        self._open_tags: List[str] = []

    def handle_starttag(self, tag: str, attrs: List[Tuple[str, str]]) -> None:
        tag_lower = tag.lower()
        if tag_lower not in ALLOWED_TAGS:
            self._open_tags.append("")
            return

        attr_string = ""
        if attrs:
            allowed_attrs = []
            for name, value in attrs:
                name_lower = name.lower()
                if name_lower == "class":
                    filtered = _filter_allowed_classes(value)
                    if filtered:
                        allowed_attrs.append(("class", filtered))
            if allowed_attrs:
                attr_string = "".join(
                    f" {escape(attr)}=\"{escape(val)}\"" for attr, val in allowed_attrs
                )

        if tag_lower == "hr":
            self.parts.append(f"<{tag_lower}{attr_string}>")
            self._open_tags.append("")
            return

        self.parts.append(f"<{tag_lower}{attr_string}>")
        self._open_tags.append(tag_lower)

    def handle_endtag(self, tag: str) -> None:
        if not self._open_tags:
            return
        open_tag = self._open_tags.pop()
        if open_tag:
            self.parts.append(f"</{open_tag}>")

    def handle_data(self, data: str) -> None:
        if data:
            self.parts.append(escape(data))

    def handle_entityref(self, name: str) -> None:
        self.parts.append(f"&{name};")

    def handle_charref(self, name: str) -> None:
        self.parts.append(f"&#{name};")


def _sanitize_analysis_html(text: str) -> str:
    sanitizer = _AnalyzerHTMLSanitizer()
    sanitizer.feed(text)
    sanitizer.close()
    sanitized = "".join(sanitizer.parts)
    return re.sub(r"<style.*?>.*?</style>", "", sanitized, flags=re.IGNORECASE | re.DOTALL)


def _numeric_class(token: str) -> str:
    cleaned = token.strip()
    if not cleaned:
        return "neutral"

    normalized = cleaned.replace(",", ".")
    stripped = re.sub(r"[^0-9+\-\.]+", "", normalized)
    try:
        number = float(stripped)
    except ValueError:
        return "neutral"

    if number < 0:
        return "negative"
    if number > 0:
        return "positive"
    return "neutral"


def _trim_trailing_breaks(html: str) -> str:
    return re.sub(r"(?:<br\s*/?>\s*)+$", "", html)


def _wrap_with_container(body: str) -> str:
    """Ensure the analysis output is wrapped in the themed container."""

    if re.search(r"class\s*=\s*['\"]analysis-container['\"]", body):
        return body
    return f"<div class='analysis-container'>{body}</div>"


def _append_caret(html: str) -> str:
    """Append a blinking caret to indicate streaming output."""

    caret = "<span class='analysis-caret'>|</span>"
    if caret in html:
        return html
    updated = re.sub(r"(</div>\s*</div>\s*)$", caret + r"\1", html, count=1)
    if updated == html:
        return html + caret
    return updated