import { useEffect, useState } from "react";
import type { BudgetPolicySummary } from "@paperclipai/shared";
import { AlertTriangle, PauseCircle, ShieldAlert, Wallet } from "lucide-react";
import { cn, formatCents } from "../lib/utils";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Input } from "@/components/ui/input";

function centsInputValue(value: number) {
  return (value / 100).toFixed(2);
}

function parseDollarInput(value: string) {
  const normalized = value.trim();
  if (normalized.length === 0) return 0;
  const parsed = Number(normalized);
  if (!Number.isFinite(parsed) || parsed < 0) return null;
  return Math.round(parsed * 100);
}

function windowLabel(windowKind: BudgetPolicySummary["windowKind"]) {
  return windowKind === "lifetime" ? "Lifetime budget" : "Monthly UTC budget";
}

function statusTone(status: BudgetPolicySummary["status"]) {
  if (status === "hard_stop") return "text-red-300 border-red-500/30 bg-red-500/10";
  if (status === "warning") return "text-amber-200 border-amber-500/30 bg-amber-500/10";
  return "text-emerald-200 border-emerald-500/30 bg-emerald-500/10";
}

export function BudgetPolicyCard({
  summary,
  onSave,
  isSaving,
  compact = false,
}: {
  summary: BudgetPolicySummary;
  onSave?: (amountCents: number) => void;
  isSaving?: boolean;
  compact?: boolean;
}) {
  const [draftBudget, setDraftBudget] = useState(centsInputValue(summary.amount));

  useEffect(() => {
    setDraftBudget(centsInputValue(summary.amount));
  }, [summary.amount]);

  const parsedDraft = parseDollarInput(draftBudget);
  const canSave = typeof parsedDraft === "number" && parsedDraft !== summary.amount && Boolean(onSave);
  const progress = summary.amount > 0 ? Math.min(100, summary.utilizationPercent) : 0;
  const StatusIcon = summary.status === "hard_stop" ? ShieldAlert : summary.status === "warning" ? AlertTriangle : Wallet;

  return (
    <Card className={cn("overflow-hidden border-border/70 bg-card/80", compact ? "" : "shadow-[0_20px_80px_-40px_rgba(0,0,0,0.55)]")}>
      <CardHeader className={cn("gap-3", compact ? "px-4 pt-4 pb-2" : "px-5 pt-5 pb-3")}>
        <div className="flex items-start justify-between gap-3">
          <div>
            <div className="text-[11px] uppercase tracking-[0.22em] text-muted-foreground">
              {summary.scopeType}
            </div>
            <CardTitle className="mt-1 text-base">{summary.scopeName}</CardTitle>
            <CardDescription className="mt-1">{windowLabel(summary.windowKind)}</CardDescription>
          </div>
          <div className={cn("inline-flex items-center gap-2 rounded-full border px-3 py-1 text-[11px] uppercase tracking-[0.18em]", statusTone(summary.status))}>
            <StatusIcon className="h-3.5 w-3.5" />
            {summary.paused ? "Paused" : summary.status === "warning" ? "Warning" : summary.status === "hard_stop" ? "Hard stop" : "Healthy"}
          </div>
        </div>
      </CardHeader>
      <CardContent className={cn("space-y-4", compact ? "px-4 pb-4 pt-0" : "px-5 pb-5 pt-0")}>
        <div className="grid gap-3 sm:grid-cols-2">
          <div className="rounded-xl border border-border/70 bg-black/[0.18] px-4 py-3">
            <div className="text-[11px] uppercase tracking-[0.18em] text-muted-foreground">Observed</div>
            <div className="mt-2 text-xl font-semibold tabular-nums">{formatCents(summary.observedAmount)}</div>
            <div className="mt-1 text-xs text-muted-foreground">
              {summary.amount > 0 ? `${summary.utilizationPercent}% of limit` : "No cap configured"}
            </div>
          </div>
          <div className="rounded-xl border border-border/70 bg-black/[0.18] px-4 py-3">
            <div className="text-[11px] uppercase tracking-[0.18em] text-muted-foreground">Budget</div>
            <div className="mt-2 text-xl font-semibold tabular-nums">
              {summary.amount > 0 ? formatCents(summary.amount) : "Disabled"}
            </div>
            <div className="mt-1 text-xs text-muted-foreground">
              Soft alert at {summary.warnPercent}%{summary.paused && summary.pauseReason ? ` · ${summary.pauseReason} pause` : ""}
            </div>
          </div>
        </div>

        <div className="space-y-2">
          <div className="flex items-center justify-between text-xs text-muted-foreground">
            <span>Remaining</span>
            <span>{summary.amount > 0 ? formatCents(summary.remainingAmount) : "Unlimited"}</span>
          </div>
          <div className="h-2 overflow-hidden rounded-full bg-muted/70">
            <div
              className={cn(
                "h-full rounded-full transition-[width,background-color] duration-200",
                summary.status === "hard_stop"
                  ? "bg-red-400"
                  : summary.status === "warning"
                    ? "bg-amber-300"
                    : "bg-emerald-300",
              )}
              style={{ width: `${progress}%` }}
            />
          </div>
        </div>

        {summary.paused ? (
          <div className="flex items-start gap-2 rounded-xl border border-red-500/30 bg-red-500/10 px-3 py-2 text-sm text-red-100">
            <PauseCircle className="mt-0.5 h-4 w-4 shrink-0" />
            <div>
              {summary.scopeType === "project"
                ? "Execution is paused for this project until the budget is raised or the incident is dismissed."
                : "Heartbeats are paused for this scope until the budget is raised or the incident is dismissed."}
            </div>
          </div>
        ) : null}

        {onSave ? (
          <div className="rounded-xl border border-border/70 bg-background/50 p-3">
            <div className="flex flex-col gap-3 sm:flex-row sm:items-end">
              <div className="min-w-0 flex-1">
                <label className="text-[11px] uppercase tracking-[0.18em] text-muted-foreground">
                  Budget (USD)
                </label>
                <Input
                  value={draftBudget}
                  onChange={(event) => setDraftBudget(event.target.value)}
                  className="mt-2"
                  inputMode="decimal"
                  placeholder="0.00"
                />
              </div>
              <Button
                onClick={() => {
                  if (typeof parsedDraft === "number" && onSave) onSave(parsedDraft);
                }}
                disabled={!canSave || isSaving || parsedDraft === null}
              >
                {isSaving ? "Saving..." : summary.amount > 0 ? "Update budget" : "Set budget"}
              </Button>
            </div>
            {parsedDraft === null ? (
              <p className="mt-2 text-xs text-destructive">Enter a valid non-negative dollar amount.</p>
            ) : null}
          </div>
        ) : null}
      </CardContent>
    </Card>
  );
}