from typing import Any, Dict, List, Tuple

import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.axes import Axes
from matplotlib.font_manager import FontProperties

import numpy as np
import matplotlib.dates as mdates
from dataclasses import dataclass
from typing import Optional

from .base import Frame, BigFrame, ModuleResult

MONEY_UNITS = {"€", "eur", "EUR", "euro", "EURO"}

def _is_money_unit(u: str) -> bool:
    return str(u).strip() in MONEY_UNITS

def compute_group_distribution(df: pd.DataFrame):
    work = df.copy()
    work = work.explode("dist_groups")
    work["group"] = work["dist_groups"].fillna("").astype(str).str.strip()
    work = work[work["group"] != ""]

    work["flag"] = work["group_flag"].astype(str).str.strip().str.upper()
    work["debitor"] = work["debitor"].astype(str).str.strip()

    contrib = work[work["flag"] == "C"].copy()
    if len(contrib) > 0:
        bad_units = contrib[~contrib["unit"].apply(_is_money_unit)]
        if len(bad_units) > 0:
            raise ValueError(
                "Contribution (C) muss Geld-Einheit haben (z.B. € / EUR). "
                f"Problemzeilen:\n{bad_units[['date','debitor','group','position','val','unit']]}"
            )

    usage = work[work["flag"] == "U"].copy()

    contrib_by_gp = contrib.groupby(["group", "debitor"])["val"].sum().rename("contributed").reset_index()
    contrib_tot = contrib.groupby("group")["val"].sum().rename("total_contrib").reset_index()

    usage_by_gp = usage.groupby(["group", "debitor"])["val"].sum().rename("usage").reset_index()
    usage_tot = usage.groupby("group")["val"].sum().rename("total_usage").reset_index()
    usage_unit = usage.groupby("group")["unit"].agg(lambda s: s.dropna().astype(str).unique().tolist()).reset_index()
    usage_unit = usage_unit.rename(columns={"unit": "usage_units"})

    participants = work.groupby("group")["debitor"].agg(lambda s: sorted(set(s.tolist()))).reset_index()
    participants = participants.rename(columns={"debitor": "participants"})

    summary = (
        participants.merge(contrib_tot, on="group", how="left")
        .merge(usage_tot, on="group", how="left")
        .merge(usage_unit, on="group", how="left")
    )
    summary["total_contrib"] = summary["total_contrib"].fillna(0.0)
    summary["total_usage"] = summary["total_usage"].fillna(0.0)
    summary["has_usage"] = summary["total_usage"].apply(lambda x: x > 0)
    summary["mode"] = summary.apply(lambda r: "usage" if r["has_usage"] else "equal", axis=1)

    detail = (
        pd.DataFrame({"group": work["group"].unique()})
        .assign(key=1)
        .merge(pd.DataFrame({"debitor": work["debitor"].unique()}).assign(key=1), on="key")
        .drop(columns=["key"])
    )
    gp_debitor = work[["group", "debitor"]].drop_duplicates()
    detail = detail.merge(gp_debitor, on=["group", "debitor"], how="inner")

    detail = detail.merge(contrib_by_gp, on=["group", "debitor"], how="left").merge(usage_by_gp, on=["group", "debitor"], how="left")
    detail["contributed"] = detail["contributed"].fillna(0.0)
    detail["usage"] = detail["usage"].fillna(0.0)

    shares = []
    for _, row in summary.iterrows():
        g = row["group"]
        total_c = float(row["total_contrib"] or 0.0)
        parts = row["participants"] or []
        n = len(parts) if parts else 0

        g_detail = detail[detail["group"] == g].copy()
        g_has_any_u = (usage["group"] == g).any()

        if g_has_any_u:
            total_u = float(g_detail["usage"].sum())
            if total_u > 0:
                g_detail["share"] = g_detail["usage"] / total_u * total_c
                mode = "usage"
            else:
                # fallback: gleichmäßig unter Teilnehmern der Gruppe
                g_detail["share"] = (total_c / n) if n else 0.0
                mode = "equal(fallback)"
        else:
            g_detail["share"] = (total_c / n) if n else 0.0
            mode = "equal"

        g_detail["mode"] = mode
        shares.append(g_detail[["group", "debitor", "share", "mode"]])

    shares_df = pd.concat(shares, ignore_index=True) if shares else pd.DataFrame(columns=["group","debitor","share","mode"])
    detail = detail.merge(shares_df, on=["group", "debitor"], how="left")
    detail["share"] = detail["share"].fillna(0.0)
    detail["balance"] = detail["contributed"] - detail["share"]

    per_debitor = detail.groupby("debitor")[["contributed", "share", "balance"]].sum().reset_index()
    per_debitor = per_debitor.sort_values("debitor")

    has_any_u = usage.groupby("group").size().rename("u_count").reset_index()
    summary = summary.merge(has_any_u, on="group", how="left")
    summary["u_count"] = summary["u_count"].fillna(0).astype(int)
    summary["mode"] = summary["u_count"].apply(lambda c: "usage" if c > 0 else "equal")

    return summary, per_debitor, detail

@dataclass
class GroupTimeSeries:
    group: str
    times: pd.DatetimeIndex
    participants: List[str]
    usage_units: List[str]
    xlim_start: pd.Timestamp
    xlim_end: pd.Timestamp
    contrib_cum: Dict[str, pd.Series]
    usage_cum: Dict[str, pd.Series]
    share_cum: Dict[str, pd.Series]
    ratio: Dict[str, pd.Series]


def _auto_time_limits(tmin: pd.Timestamp, tmax: pd.Timestamp) -> tuple[pd.Timestamp, pd.Timestamp]:
    dt = tmax - tmin
    if dt <= pd.Timedelta(0):
        margin = pd.Timedelta(minutes=30)
    else:
        margin = dt * 0.05
    return (tmin - margin, tmax + margin)


def _prepare_group_timeseries(df: pd.DataFrame, group: str) -> Optional[GroupTimeSeries]:
    work = df.copy().explode("dist_groups")
    work["group"] = work["dist_groups"].fillna("").astype(str).str.strip()
    work = work[work["group"] == group].copy()

    work = work[pd.notna(work["date"])]
    if work.empty:
        return None

    work["debitor"] = work["debitor"].astype(str).str.strip()
    work["flag"] = work["group_flag"].astype(str).str.strip().str.upper()

    participants = sorted(work["debitor"].unique().tolist())

    times = pd.DatetimeIndex(sorted(work["date"].unique()))
    tmin, tmax = times.min(), times.max()
    x0, x1 = _auto_time_limits(tmin, tmax)

    times = times.union(pd.DatetimeIndex([x0, x1])).sort_values()

    usage_units = sorted(
        work.loc[work["flag"] == "U", "unit"]
            .dropna()
            .astype(str)
            .str.strip()
            .unique()
            .tolist()
    )

    contrib_cum: Dict[str, pd.Series] = {}
    usage_cum: Dict[str, pd.Series] = {}

    for p in participants:
        c = work[(work["debitor"] == p) & (work["flag"] == "C")].copy()
        u = work[(work["debitor"] == p) & (work["flag"] == "U")].copy()

        c_by_t = c.groupby("date")["val"].sum() if not c.empty else pd.Series(dtype=float)
        c_by_t = c_by_t.reindex(times, fill_value=0.0)
        contrib_cum[p] = c_by_t.cumsum()

        u_by_t = u.groupby("date")["val"].sum() if not u.empty else pd.Series(dtype=float)
        u_by_t = u_by_t.reindex(times, fill_value=0.0)
        usage_cum[p] = u_by_t.cumsum()

    total_contrib = sum((contrib_cum[p] for p in participants), start=pd.Series(0.0, index=times))
    total_usage = sum((usage_cum[p] for p in participants), start=pd.Series(0.0, index=times))

    has_any_u = (work["flag"] == "U").any()
    n = len(participants) if participants else 1

    share_cum: Dict[str, pd.Series] = {}
    if has_any_u:
        for p in participants:
            usage_p = usage_cum[p]
            with np.errstate(divide="ignore", invalid="ignore"):
                share_usage = total_contrib * (usage_p / total_usage.replace(0.0, np.nan))
            share_equal = total_contrib / float(n)
            share = share_usage.where(total_usage > 0, share_equal)
            share_cum[p] = share.fillna(0.0)
    else:
        equal = total_contrib / float(n)
        for p in participants:
            share_cum[p] = equal

    ratio: Dict[str, pd.Series] = {}
    for p in participants:
        denom = contrib_cum[p].astype(float)
        r = share_cum[p].astype(float) / denom.where(denom > 0, np.nan)
        ratio[p] = r.fillna(0.0)

    return GroupTimeSeries(
        group=group,
        times=times,
        participants=participants,
        usage_units=usage_units,
        xlim_start=x0,
        xlim_end=x1,
        contrib_cum=contrib_cum,
        usage_cum=usage_cum,
        share_cum=share_cum,
        ratio=ratio,
    )


@dataclass
class GroupChartBigFrame(BigFrame):
    gts: GroupTimeSeries
    kind: str

    def render(self, ax: Axes, mono_font: FontProperties) -> None:
        ax.axis("on")

        locator = mdates.AutoDateLocator(minticks=3, maxticks=7)
        formatter = mdates.ConciseDateFormatter(locator)
        ax.xaxis.set_major_locator(locator)
        ax.xaxis.set_major_formatter(formatter)
        ax.xaxis.get_offset_text().set_visible(False)

        ax.set_xlim(self.gts.xlim_start, self.gts.xlim_end)

        if self.kind == "usage_cum":
            series_map = self.gts.usage_cum
            unit = "/".join(self.gts.usage_units) if self.gts.usage_units else ""
            ax.set_ylabel(f"Usage cumulative {unit}".strip(), fontproperties=mono_font)

        elif self.kind == "contrib_cum":
            series_map = self.gts.contrib_cum
            ax.set_ylabel("Contribution cumulative €", fontproperties=mono_font)

        elif self.kind == "share_cum":
            series_map = self.gts.share_cum
            ax.set_ylabel("Share cumulative €", fontproperties=mono_font)

        elif self.kind == "ratio":
            series_map = self.gts.ratio
            ax.set_ylabel("Share / Contribution ratio (logarithmic)", fontproperties=mono_font)
            ax.set_yscale("log")

        else:
            raise ValueError(f"Unknown kind: {self.kind}")

        all_vals = []

        min_ratio = 1e-3

        for p in self.gts.participants:
            y = series_map[p].copy()

            if self.kind == "ratio":
                y = y.replace([np.inf, -np.inf], np.nan)
                y = y.fillna(min_ratio)
                y = y.clip(lower=min_ratio)
            else:
                y = y.replace([np.inf, -np.inf], np.nan).fillna(0.0)

            ax.plot(self.gts.times, y.values, label=p, linewidth=1, drawstyle="steps-post")

            v = y.values
            v = v[np.isfinite(v)]
            if v.size:
                all_vals.append(v)

        if all_vals:
            vv = np.concatenate(all_vals)

            if self.kind in ("usage_cum", "contrib_cum", "share_cum"):
                vmax = float(np.nanmax(vv)) if vv.size else 0.0
                if vmax <= 0:
                    ax.set_ylim(0, 1)
                else:
                    ax.set_ylim(0, vmax * 1.08)

            elif self.kind == "ratio":
                vpos = vv[vv > 0]
                if vpos.size:
                    vmin = float(np.nanmin(vpos))
                    vmax = float(np.nanmax(vpos))
                    ax.set_ylim(vmin / 1.5, vmax * 1.5)

        ax.grid(True, alpha=0.2)

        leg = ax.legend(prop=mono_font, fontsize=7, loc="best", ncols=2)
        if leg:
            for t in leg.get_texts():
                t.set_fontproperties(mono_font)

        for tick in ax.get_xticklabels() + ax.get_yticklabels():
            tick.set_fontproperties(mono_font)

@dataclass
class TextFrame(Frame):
    text: str

    def render(self, ax: Axes, mono_font: FontProperties) -> None:
        ax.text(0, 1, self.text, va="top", ha="left", fontproperties=mono_font)

@dataclass
class PlotBigFrame(BigFrame):
    per_debitor: pd.DataFrame

    def render(self, ax: Axes, mono_font: FontProperties) -> None:
        ax.axis("on")
        plot_df = self.per_debitor.set_index("debitor")[["contributed", "share"]]
        plot_df.plot.bar(ax=ax)
        ax.tick_params(axis="x", rotation=0)
        leg = ax.legend(prop=mono_font)
        if leg:
            for t in leg.get_texts():
                t.set_fontproperties(mono_font)

        for tick in ax.get_xticklabels() + ax.get_yticklabels():
            tick.set_fontproperties(mono_font)

        ax.xaxis.label.set_fontproperties(mono_font)
        ax.yaxis.label.set_fontproperties(mono_font)


class GeneralModule:
    name = "general"

    def process(self, df: pd.DataFrame, context: Dict[str, Any]) -> ModuleResult:
        want_pdf = bool(context.get("want_pdf", True))

        mono_font = context.get("mono_font") or FontProperties(family="DejaVu Sans Mono", size=8)

        group_summary, per_debitor, detail = compute_group_distribution(df)

        balance = {r["debitor"]: float(r["balance"]) for _, r in per_debitor.iterrows()}
        payments = self._minimize_payments(balance)

        summary_lines = []
        summary_lines.append("General")
        summary_lines.append("")
        summary_lines.append("Goups:")
        for _, r in group_summary.sort_values("group").iterrows():
            g = r["group"]
            total_c = float(r.get("total_contrib", 0.0))
            u_count = int(r.get("u_count", 0))
            mode = "usage" if u_count > 0 else "equal"
            participants = r.get("participants", []) or []
            summary_lines.append(f"  - {g}: {total_c:.2f} €; mode={mode}; participants={len(participants)}")

        summary_lines.append("")
        summary_lines.append("Debitors (total):")
        for _, r in per_debitor.sort_values("debitor").iterrows():
            summary_lines.append(
                f"  - {r['debitor']}: contributed={r['contributed']:.2f} €; share={r['share']:.2f} €; balance={r['balance']:.2f} €"
            )

        summary_lines.append("")
        summary_lines.append("Compensation (minimized):")
        if payments:
            for p, r, a in payments:
                summary_lines.append(f"  - {p} → {r}: {a:.2f} €")
        else:
            summary_lines.append("  (No compensation required)")

        summary_text = "\n".join(summary_lines)

        frames: List[Frame] = []
        bigframes: List[BigFrame] = []
        pages: List[plt.Figure] = []

        if want_pdf:
            frames.extend(self._make_frames(group_summary, per_debitor, payments))

            bigframes.append(
                PlotBigFrame(
                    title="General – Shares vs. Contributions (total)",
                    per_debitor=per_debitor.copy(),
                )
            )

            for g in sorted(group_summary["group"].unique().tolist()):
                gts = _prepare_group_timeseries(df, g)
                if not gts:
                    continue

                bigframes.append(GroupChartBigFrame(
                    title=f"{g} – Cumulative usage per debitor",
                    gts=gts,
                    kind="usage_cum",
                ))
                bigframes.append(GroupChartBigFrame(
                    title=f"{g} – Cumulative contributions per debitor",
                    gts=gts,
                    kind="contrib_cum",
                ))
                bigframes.append(GroupChartBigFrame(
                    title=f"{g} – Share per debitor",
                    gts=gts,
                    kind="share_cum",
                ))
                bigframes.append(GroupChartBigFrame(
                    title=f"{g} – Share / Contribution ratio (logarithmic)",
                    gts=gts,
                    kind="ratio",
                ))

            pages.extend(self._make_pages(group_summary, per_debitor, detail, mono_font))

        return ModuleResult(summary_text=summary_text, frames=frames, bigframes=bigframes, pages=pages)

    def _minimize_payments(self, balance: Dict[str, float]):
        receivers = []
        payers = []
        for p, amt in balance.items():
            a = round(float(amt), 2)
            if a > 0:
                receivers.append([p, a])
            elif a < 0:
                payers.append([p, -a])

        out = []
        i = j = 0
        while i < len(payers) and j < len(receivers):
            payer, avail = payers[i]
            recv, need = receivers[j]
            pay = min(avail, need)
            out.append((payer, recv, pay))
            payers[i][1] -= pay
            receivers[j][1] -= pay
            if round(payers[i][1], 2) == 0:
                i += 1
            if round(receivers[j][1], 2) == 0:
                j += 1
        return out

    def _make_frames(self, group_summary: pd.DataFrame, per_debitor: pd.DataFrame, payments: List[Tuple[str,str,float]]) -> List[Frame]:
        lines = ["Groups:"]
        for _, r in group_summary.sort_values("group").iterrows():
            g = r["group"]
            total_c = float(r.get("total_contrib", 0.0))
            u_count = int(r.get("u_count", 0))
            parts = r.get("participants", [])
            mode = "usage" if u_count > 0 else "equal"
            lines.append(f"- {g}: {total_c:.2f} €; mode={mode}; participants={len(parts)}")

        f1 = TextFrame(title="General: Groups", text="\n".join(lines))

        lines = ["Debitor total:", "debitor | contributed | share | balance"]
        for _, r in per_debitor.iterrows():
            lines.append(f"{r['debitor']} | {r['contributed']:.2f} € | {r['share']:.2f} € | {r['balance']:.2f} €")
        f2 = TextFrame(title="General: Debitors", text="\n".join(lines))

        lines = ["Compensation (minimized):"]
        if payments:
            for p, r, a in payments:
                lines.append(f"{p} → {r}: {a:.2f} €")
        else:
            lines.append("(No compensation required)")
        f3 = TextFrame(title="General: Compensation", text="\n".join(lines))

        return [f1, f2, f3]

    def _make_pages(self, group_summary, per_debitor, detail, mono_font) -> List[plt.Figure]:
        pages: List[plt.Figure] = []

        for g in sorted(detail["group"].unique().tolist()):
            gdet = detail[detail["group"] == g].sort_values("debitor")
            total_c = float(group_summary[group_summary["group"] == g]["total_contrib"].iloc[0]) if (group_summary["group"] == g).any() else 0.0
            u_count = int(group_summary[group_summary["group"] == g]["u_count"].iloc[0]) if (group_summary["group"] == g).any() else 0
            mode = "usage" if u_count > 0 else "equal"

            lines = [
                f"Group: {g}",
                f"Total Contribution: {total_c:.2f} €",
                f"Mode: {mode}",
                "",
                "debitor | contributed | usage | share | balance",
            ]
            for _, r in gdet.iterrows():
                lines.append(
                    f"{r['debitor']} | {r['contributed']:.2f} € | {r['usage']:.4f} | {r['share']:.2f} € | {r['balance']:.2f} €"
                )

            fig, ax = plt.subplots(figsize=(8.27, 11.69))
            ax.axis("off")
            ax.text(0, 1, "\n".join(lines), va="top", ha="left", fontproperties=mono_font)
            pages.append(fig)

        return pages