"""Chart Data Extractor: extract chart-ready data from content blocks and tables."""
import re
from typing import List, Optional

from pydantic import BaseModel

from models.content_models import ContentBlock, ContentBlockType
from services.attachment_parser_service import TableData


class ChartSeries(BaseModel):
    name: str
    values: List[float]


class ChartData(BaseModel):
    chart_type: str  # bar, column, line, pie, doughnut, area, scatter, gantt, waterfall
    title: str
    categories: List[str]
    series: List[ChartSeries]
    unit: Optional[str] = None


# --- Public API ---


def extract(
    content_block: ContentBlock,
    table_data: Optional[TableData] = None,
) -> Optional[ChartData]:
    """Extract chart data from a content block and/or associated table.

    Returns ChartData if chartable data is found, else None.
    """
    if table_data and table_data.rows and table_data.headers:
        return _chart_from_table(table_data)

    if content_block.type == ContentBlockType.metric:
        return _chart_from_metrics(content_block)

    return None


# --- Table → ChartData ---


def _chart_from_table(td: TableData) -> Optional[ChartData]:
    """Convert a TableData into ChartData.

    Heuristic: first column = categories, remaining numeric columns = series.
    """
    if not td.rows or len(td.headers) < 2:
        return None

    # Determine which columns are numeric (by checking majority of rows)
    numeric_cols = []
    for col_idx in range(1, len(td.headers)):
        numeric_count = 0
        for row in td.rows:
            if col_idx < len(row):
                val = row[col_idx]
                if _to_float(val) is not None:
                    numeric_count += 1
        if numeric_count >= len(td.rows) * 0.5:
            numeric_cols.append(col_idx)

    if not numeric_cols:
        return None

    categories = []
    for row in td.rows:
        categories.append(str(row[0]) if row else "")

    series_list: List[ChartSeries] = []
    for col_idx in numeric_cols:
        values = []
        for row in td.rows:
            val = row[col_idx] if col_idx < len(row) else 0
            values.append(_to_float(val) or 0.0)
        series_list.append(
            ChartSeries(name=td.headers[col_idx], values=values)
        )

    chart_type = _recommend_chart_type(categories, series_list, td)
    title = td.title or td.sheet_name or "Chart"

    return ChartData(
        chart_type=chart_type,
        title=title,
        categories=categories,
        series=series_list,
    )


# --- Metric block → ChartData ---

_NUMBER_RE = re.compile(
    r"[\$€£¥]?\s?(\d[\d,.]*)\s?([KMBTkmbt%]?)",
)


def _chart_from_metrics(block: ContentBlock) -> Optional[ChartData]:
    """Build ChartData from a metric content block's extracted_data."""
    metrics = (block.extracted_data or {}).get("metrics", [])
    if not metrics:
        return None

    categories = []
    values = []
    unit = None

    for m in metrics:
        label = m.get("label", "").strip()
        raw_value = m.get("value", "")
        parsed = _parse_metric_value(raw_value)
        if parsed is None:
            continue

        numeric_val, val_unit = parsed
        if val_unit and not unit:
            unit = val_unit

        categories.append(label or f"Metric {len(categories) + 1}")
        values.append(numeric_val)

    if len(values) < 2:
        return None

    chart_type = "bar"
    # If all values are percentages and sum near 100, use pie
    if unit == "%" and 90 <= sum(values) <= 110:
        chart_type = "pie"

    return ChartData(
        chart_type=chart_type,
        title=block.source_section or "Key Metrics",
        categories=categories,
        series=[ChartSeries(name="Value", values=values)],
        unit=unit,
    )


# --- Chart type recommendation ---

_TIME_PATTERN = re.compile(
    r"(?:19|20)\d{2}|Q[1-4]|(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)",
    re.IGNORECASE,
)


def _recommend_chart_type(
    categories: List[str],
    series: List[ChartSeries],
    td: Optional[TableData] = None,
) -> str:
    """Auto-recommend a chart type based on data characteristics."""
    n_cats = len(categories)
    n_series = len(series)

    # Check if categories look like time periods
    time_count = sum(1 for c in categories if _TIME_PATTERN.search(c))
    is_time_series = time_count >= n_cats * 0.6

    if is_time_series:
        return "line"

    # Single series
    if n_series == 1:
        vals = series[0].values
        # Parts of a whole
        total = sum(vals)
        if 2 <= n_cats <= 8 and 90 <= total <= 110:
            return "pie"
        if n_cats <= 6:
            return "bar"
        return "column"

    # Multiple series
    if n_series == 2:
        return "bar"  # grouped bar

    return "column"


# --- Helpers ---


def _to_float(val) -> Optional[float]:
    """Convert a cell value to float, handling common formats."""
    if val is None:
        return None
    if isinstance(val, (int, float)):
        return float(val)
    if isinstance(val, str):
        cleaned = val.strip().replace(",", "").replace("$", "").replace("€", "").replace("£", "").replace("¥", "").rstrip("%")
        try:
            return float(cleaned)
        except ValueError:
            return None
    return None


def _parse_metric_value(raw: str) -> Optional[tuple]:
    """Parse a metric value string like '$2.3M' or '45%' into (float, unit)."""
    if not raw:
        return None

    raw = raw.strip()
    unit = None

    if raw.endswith("%"):
        unit = "%"
        raw = raw.rstrip("%").strip()
    elif raw[-1:].upper() in ("K", "M", "B", "T"):
        suffix = raw[-1].upper()
        multipliers = {"K": 1_000, "M": 1_000_000, "B": 1_000_000_000, "T": 1_000_000_000_000}
        raw_num = raw[:-1].strip()
        cleaned = raw_num.replace(",", "").replace("$", "").replace("€", "").replace("£", "").replace("¥", "")
        try:
            return float(cleaned) * multipliers[suffix], suffix
        except ValueError:
            return None

    cleaned = raw.replace(",", "").replace("$", "").replace("€", "").replace("£", "").replace("¥", "")
    try:
        return float(cleaned), unit
    except ValueError:
        return None