import { useEffect, useMemo, useState } from "react";
import { useNavigate } from "react-router-dom";
import { useQuery } from "@tanstack/react-query";
import { activityApi } from "../api/activity";
import { agentsApi } from "../api/agents";
import { issuesApi } from "../api/issues";
import { projectsApi } from "../api/projects";
import { goalsApi } from "../api/goals";
import { useCompany } from "../context/CompanyContext";
import { useBreadcrumbs } from "../context/BreadcrumbContext";
import { queryKeys } from "../lib/queryKeys";
import { EmptyState } from "../components/EmptyState";
import { Identity } from "../components/Identity";
import { timeAgo } from "../lib/timeAgo";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";
import { History } from "lucide-react";
import type { Agent } from "@paperclip/shared";

// Maps action → verb phrase. When the entity name is available it reads as:
//   "[Actor] commented on "Fix the bug""
// When not available, it falls back to just the verb.
const ACTION_VERBS: Record<string, string> = {
  "issue.created": "created",
  "issue.updated": "updated",
  "issue.checked_out": "checked out",
  "issue.released": "released",
  "issue.comment_added": "commented on",
  "issue.commented": "commented on",
  "issue.deleted": "deleted",
  "agent.created": "created",
  "agent.updated": "updated",
  "agent.paused": "paused",
  "agent.resumed": "resumed",
  "agent.terminated": "terminated",
  "agent.key_created": "created API key for",
  "agent.budget_updated": "updated budget for",
  "agent.runtime_session_reset": "reset session for",
  "heartbeat.invoked": "invoked heartbeat for",
  "heartbeat.cancelled": "cancelled heartbeat for",
  "approval.created": "requested approval",
  "approval.approved": "approved",
  "approval.rejected": "rejected",
  "project.created": "created",
  "project.updated": "updated",
  "project.deleted": "deleted",
  "goal.created": "created",
  "goal.updated": "updated",
  "goal.deleted": "deleted",
  "cost.reported": "reported cost for",
  "cost.recorded": "recorded cost for",
  "company.created": "created",
  "company.updated": "updated",
  "company.archived": "archived",
  "company.budget_updated": "updated budget for",
};

function entityLink(entityType: string, entityId: string): string | null {
  switch (entityType) {
    case "issue":
      return `/issues/${entityId}`;
    case "agent":
      return `/agents/${entityId}`;
    case "project":
      return `/projects/${entityId}`;
    case "goal":
      return `/goals/${entityId}`;
    case "approval":
      return `/approvals/${entityId}`;
    default:
      return null;
  }
}

function actorIdentity(actorType: string, actorId: string, agentMap: Map<string, Agent>) {
  if (actorType === "agent") {
    const agent = agentMap.get(actorId);
    return <Identity name={agent?.name ?? actorId.slice(0, 8)} size="sm" />;
  }
  if (actorType === "system") return <Identity name="System" size="sm" />;
  return <Identity name={actorId || "You"} size="sm" />;
}

export function Activity() {
  const { selectedCompanyId } = useCompany();
  const { setBreadcrumbs } = useBreadcrumbs();
  const navigate = useNavigate();
  const [filter, setFilter] = useState("all");

  useEffect(() => {
    setBreadcrumbs([{ label: "Activity" }]);
  }, [setBreadcrumbs]);

  const { data, isLoading, error } = useQuery({
    queryKey: queryKeys.activity(selectedCompanyId!),
    queryFn: () => activityApi.list(selectedCompanyId!),
    enabled: !!selectedCompanyId,
  });

  const { data: agents } = useQuery({
    queryKey: queryKeys.agents.list(selectedCompanyId!),
    queryFn: () => agentsApi.list(selectedCompanyId!),
    enabled: !!selectedCompanyId,
  });

  const { data: issues } = useQuery({
    queryKey: queryKeys.issues.list(selectedCompanyId!),
    queryFn: () => issuesApi.list(selectedCompanyId!),
    enabled: !!selectedCompanyId,
  });

  const { data: projects } = useQuery({
    queryKey: queryKeys.projects.list(selectedCompanyId!),
    queryFn: () => projectsApi.list(selectedCompanyId!),
    enabled: !!selectedCompanyId,
  });

  const { data: goals } = useQuery({
    queryKey: queryKeys.goals.list(selectedCompanyId!),
    queryFn: () => goalsApi.list(selectedCompanyId!),
    enabled: !!selectedCompanyId,
  });

  const agentMap = useMemo(() => {
    const map = new Map<string, Agent>();
    for (const a of agents ?? []) map.set(a.id, a);
    return map;
  }, [agents]);

  // Unified map: "entityType:entityId" → display name
  const entityNameMap = useMemo(() => {
    const map = new Map<string, string>();
    for (const i of issues ?? []) map.set(`issue:${i.id}`, i.title);
    for (const a of agents ?? []) map.set(`agent:${a.id}`, a.name);
    for (const p of projects ?? []) map.set(`project:${p.id}`, p.name);
    for (const g of goals ?? []) map.set(`goal:${g.id}`, g.title);
    return map;
  }, [issues, agents, projects, goals]);

  if (!selectedCompanyId) {
    return <EmptyState icon={History} message="Select a company to view activity." />;
  }

  const filtered =
    data && filter !== "all"
      ? data.filter((e) => e.entityType === filter)
      : data;

  const entityTypes = data
    ? [...new Set(data.map((e) => e.entityType))].sort()
    : [];

  return (
    <div className="space-y-4">
      <div className="flex items-center justify-end">
        <Select value={filter} onValueChange={setFilter}>
          <SelectTrigger className="w-[140px] h-8 text-xs">
            <SelectValue placeholder="Filter by type" />
          </SelectTrigger>
          <SelectContent>
            <SelectItem value="all">All types</SelectItem>
            {entityTypes.map((type) => (
              <SelectItem key={type} value={type}>
                {type.charAt(0).toUpperCase() + type.slice(1)}
              </SelectItem>
            ))}
          </SelectContent>
        </Select>
      </div>

      {isLoading && <p className="text-sm text-muted-foreground">Loading...</p>}
      {error && <p className="text-sm text-destructive">{error.message}</p>}

      {filtered && filtered.length === 0 && (
        <EmptyState icon={History} message="No activity yet." />
      )}

      {filtered && filtered.length > 0 && (
        <div className="border border-border divide-y divide-border">
          {filtered.map((event) => {
            const link = entityLink(event.entityType, event.entityId);
            const verb = ACTION_VERBS[event.action] ?? event.action.replace(/[._]/g, " ");
            const name = entityNameMap.get(`${event.entityType}:${event.entityId}`);
            return (
              <div
                key={event.id}
                className={`px-4 py-2.5 flex items-center justify-between gap-4 ${
                  link ? "cursor-pointer hover:bg-accent/50 transition-colors" : ""
                }`}
                onClick={link ? () => navigate(link) : undefined}
              >
                <div className="flex items-center gap-2 min-w-0">
                  {actorIdentity(event.actorType, event.actorId, agentMap)}
                  <span className="text-sm text-muted-foreground">{verb}</span>
                  {name && (
                    <span className="text-sm truncate">{name}</span>
                  )}
                </div>
                <span className="text-xs text-muted-foreground shrink-0">
                  {timeAgo(event.createdAt)}
                </span>
              </div>
            );
          })}
        </div>
      )}
    </div>
  );
}