import { useCallback, useEffect, useMemo, useState, useRef } from "react";
import { useParams, useNavigate, useLocation, Navigate } from "@/lib/router";
import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import { PROJECT_COLORS, isUuidLike } from "@paperclipai/shared";
import { projectsApi } from "../api/projects";
import { issuesApi } from "../api/issues";
import { agentsApi } from "../api/agents";
import { heartbeatsApi } from "../api/heartbeats";
import { assetsApi } from "../api/assets";
import { usePanel } from "../context/PanelContext";
import { useCompany } from "../context/CompanyContext";
import { useBreadcrumbs } from "../context/BreadcrumbContext";
import { queryKeys } from "../lib/queryKeys";
import { ProjectProperties, type ProjectConfigFieldKey, type ProjectFieldSaveState } from "../components/ProjectProperties";
import { InlineEditor } from "../components/InlineEditor";
import { StatusBadge } from "../components/StatusBadge";
import { IssuesList } from "../components/IssuesList";
import { PageSkeleton } from "../components/PageSkeleton";
import { PageTabBar } from "../components/PageTabBar";
import { projectRouteRef, cn } from "../lib/utils";
import { Tabs } from "@/components/ui/tabs";

/* ── Top-level tab types ── */

type ProjectTab = "overview" | "list" | "configuration";

function resolveProjectTab(pathname: string, projectId: string): ProjectTab | null {
  const segments = pathname.split("/").filter(Boolean);
  const projectsIdx = segments.indexOf("projects");
  if (projectsIdx === -1 || segments[projectsIdx + 1] !== projectId) return null;
  const tab = segments[projectsIdx + 2];
  if (tab === "overview") return "overview";
  if (tab === "configuration") return "configuration";
  if (tab === "issues") return "list";
  return null;
}

/* ── Overview tab content ── */

function OverviewContent({
  project,
  onUpdate,
  imageUploadHandler,
}: {
  project: { description: string | null; status: string; targetDate: string | null };
  onUpdate: (data: Record<string, unknown>) => void;
  imageUploadHandler?: (file: File) => Promise<string>;
}) {
  return (
    <div className="space-y-6">
      <InlineEditor
        value={project.description ?? ""}
        onSave={(description) => onUpdate({ description })}
        as="p"
        className="text-sm text-muted-foreground"
        placeholder="Add a description..."
        multiline
        imageUploadHandler={imageUploadHandler}
      />

      <div className="grid grid-cols-1 sm:grid-cols-2 gap-4 text-sm">
        <div>
          <span className="text-muted-foreground">Status</span>
          <div className="mt-1">
            <StatusBadge status={project.status} />
          </div>
        </div>
        {project.targetDate && (
          <div>
            <span className="text-muted-foreground">Target Date</span>
            <p>{project.targetDate}</p>
          </div>
        )}
      </div>
    </div>
  );
}

/* ── Color picker popover ── */

function ColorPicker({
  currentColor,
  onSelect,
}: {
  currentColor: string;
  onSelect: (color: string) => void;
}) {
  const [open, setOpen] = useState(false);
  const ref = useRef<HTMLDivElement>(null);

  useEffect(() => {
    if (!open) return;
    function handleClick(e: MouseEvent) {
      if (ref.current && !ref.current.contains(e.target as Node)) {
        setOpen(false);
      }
    }
    document.addEventListener("mousedown", handleClick);
    return () => document.removeEventListener("mousedown", handleClick);
  }, [open]);

  return (
    <div className="relative" ref={ref}>
      <button
        onClick={() => setOpen(!open)}
        className="shrink-0 h-5 w-5 rounded-md cursor-pointer hover:ring-2 hover:ring-foreground/20 transition-[box-shadow]"
        style={{ backgroundColor: currentColor }}
        aria-label="Change project color"
      />
      {open && (
        <div className="absolute top-full left-0 mt-2 p-2 bg-popover border border-border rounded-lg shadow-lg z-50 w-max">
          <div className="grid grid-cols-5 gap-1.5">
            {PROJECT_COLORS.map((color) => (
              <button
                key={color}
                onClick={() => {
                  onSelect(color);
                  setOpen(false);
                }}
                className={`h-6 w-6 rounded-md cursor-pointer transition-[transform,box-shadow] duration-150 hover:scale-110 ${
                  color === currentColor
                    ? "ring-2 ring-foreground ring-offset-1 ring-offset-background"
                    : "hover:ring-2 hover:ring-foreground/30"
                }`}
                style={{ backgroundColor: color }}
                aria-label={`Select color ${color}`}
              />
            ))}
          </div>
        </div>
      )}
    </div>
  );
}

/* ── List (issues) tab content ── */

function ProjectIssuesList({ projectId, companyId }: { projectId: string; companyId: string }) {
  const queryClient = useQueryClient();

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

  const { data: liveRuns } = useQuery({
    queryKey: queryKeys.liveRuns(companyId),
    queryFn: () => heartbeatsApi.liveRunsForCompany(companyId),
    enabled: !!companyId,
    refetchInterval: 5000,
  });

  const liveIssueIds = useMemo(() => {
    const ids = new Set<string>();
    for (const run of liveRuns ?? []) {
      if (run.issueId) ids.add(run.issueId);
    }
    return ids;
  }, [liveRuns]);

  const { data: issues, isLoading, error } = useQuery({
    queryKey: queryKeys.issues.listByProject(companyId, projectId),
    queryFn: () => issuesApi.list(companyId, { projectId }),
    enabled: !!companyId,
  });

  const updateIssue = useMutation({
    mutationFn: ({ id, data }: { id: string; data: Record<string, unknown> }) =>
      issuesApi.update(id, data),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: queryKeys.issues.listByProject(companyId, projectId) });
      queryClient.invalidateQueries({ queryKey: queryKeys.issues.list(companyId) });
    },
  });

  return (
    <IssuesList
      issues={issues ?? []}
      isLoading={isLoading}
      error={error as Error | null}
      agents={agents}
      liveIssueIds={liveIssueIds}
      projectId={projectId}
      viewStateKey={`paperclip:project-view:${projectId}`}
      onUpdateIssue={(id, data) => updateIssue.mutate({ id, data })}
    />
  );
}

/* ── Main project page ── */

export function ProjectDetail() {
  const { companyPrefix, projectId, filter } = useParams<{
    companyPrefix?: string;
    projectId: string;
    filter?: string;
  }>();
  const { companies, selectedCompanyId, setSelectedCompanyId } = useCompany();
  const { closePanel } = usePanel();
  const { setBreadcrumbs } = useBreadcrumbs();
  const queryClient = useQueryClient();
  const navigate = useNavigate();
  const location = useLocation();
  const [fieldSaveStates, setFieldSaveStates] = useState<Partial<Record<ProjectConfigFieldKey, ProjectFieldSaveState>>>({});
  const fieldSaveRequestIds = useRef<Partial<Record<ProjectConfigFieldKey, number>>>({});
  const fieldSaveTimers = useRef<Partial<Record<ProjectConfigFieldKey, ReturnType<typeof setTimeout>>>>({});
  const routeProjectRef = projectId ?? "";
  const routeCompanyId = useMemo(() => {
    if (!companyPrefix) return null;
    const requestedPrefix = companyPrefix.toUpperCase();
    return companies.find((company) => company.issuePrefix.toUpperCase() === requestedPrefix)?.id ?? null;
  }, [companies, companyPrefix]);
  const lookupCompanyId = routeCompanyId ?? selectedCompanyId ?? undefined;
  const canFetchProject = routeProjectRef.length > 0 && (isUuidLike(routeProjectRef) || Boolean(lookupCompanyId));

  const activeTab = routeProjectRef ? resolveProjectTab(location.pathname, routeProjectRef) : null;

  const { data: project, isLoading, error } = useQuery({
    queryKey: [...queryKeys.projects.detail(routeProjectRef), lookupCompanyId ?? null],
    queryFn: () => projectsApi.get(routeProjectRef, lookupCompanyId),
    enabled: canFetchProject,
  });
  const canonicalProjectRef = project ? projectRouteRef(project) : routeProjectRef;
  const projectLookupRef = project?.id ?? routeProjectRef;
  const resolvedCompanyId = project?.companyId ?? selectedCompanyId;

  useEffect(() => {
    if (!project?.companyId || project.companyId === selectedCompanyId) return;
    setSelectedCompanyId(project.companyId, { source: "route_sync" });
  }, [project?.companyId, selectedCompanyId, setSelectedCompanyId]);

  const invalidateProject = () => {
    queryClient.invalidateQueries({ queryKey: queryKeys.projects.detail(routeProjectRef) });
    queryClient.invalidateQueries({ queryKey: queryKeys.projects.detail(projectLookupRef) });
    if (resolvedCompanyId) {
      queryClient.invalidateQueries({ queryKey: queryKeys.projects.list(resolvedCompanyId) });
    }
  };

  const updateProject = useMutation({
    mutationFn: (data: Record<string, unknown>) =>
      projectsApi.update(projectLookupRef, data, resolvedCompanyId ?? lookupCompanyId),
    onSuccess: invalidateProject,
  });

  const uploadImage = useMutation({
    mutationFn: async (file: File) => {
      if (!resolvedCompanyId) throw new Error("No company selected");
      return assetsApi.uploadImage(resolvedCompanyId, file, `projects/${projectLookupRef || "draft"}`);
    },
  });

  useEffect(() => {
    setBreadcrumbs([
      { label: "Projects", href: "/projects" },
      { label: project?.name ?? routeProjectRef ?? "Project" },
    ]);
  }, [setBreadcrumbs, project, routeProjectRef]);

  useEffect(() => {
    if (!project) return;
    if (routeProjectRef === canonicalProjectRef) return;
    if (activeTab === "overview") {
      navigate(`/projects/${canonicalProjectRef}/overview`, { replace: true });
      return;
    }
    if (activeTab === "configuration") {
      navigate(`/projects/${canonicalProjectRef}/configuration`, { replace: true });
      return;
    }
    if (activeTab === "list") {
      if (filter) {
        navigate(`/projects/${canonicalProjectRef}/issues/${filter}`, { replace: true });
        return;
      }
      navigate(`/projects/${canonicalProjectRef}/issues`, { replace: true });
      return;
    }
    navigate(`/projects/${canonicalProjectRef}`, { replace: true });
  }, [project, routeProjectRef, canonicalProjectRef, activeTab, filter, navigate]);

  useEffect(() => {
    closePanel();
    return () => closePanel();
  }, [closePanel]);

  useEffect(() => {
    return () => {
      Object.values(fieldSaveTimers.current).forEach((timer) => {
        if (timer) clearTimeout(timer);
      });
    };
  }, []);

  const setFieldState = useCallback((field: ProjectConfigFieldKey, state: ProjectFieldSaveState) => {
    setFieldSaveStates((current) => ({ ...current, [field]: state }));
  }, []);

  const scheduleFieldReset = useCallback((field: ProjectConfigFieldKey, delayMs: number) => {
    const existing = fieldSaveTimers.current[field];
    if (existing) clearTimeout(existing);
    fieldSaveTimers.current[field] = setTimeout(() => {
      setFieldSaveStates((current) => {
        const next = { ...current };
        delete next[field];
        return next;
      });
      delete fieldSaveTimers.current[field];
    }, delayMs);
  }, []);

  const updateProjectField = useCallback(async (field: ProjectConfigFieldKey, data: Record<string, unknown>) => {
    const requestId = (fieldSaveRequestIds.current[field] ?? 0) + 1;
    fieldSaveRequestIds.current[field] = requestId;
    setFieldState(field, "saving");
    try {
      await projectsApi.update(projectLookupRef, data, resolvedCompanyId ?? lookupCompanyId);
      invalidateProject();
      if (fieldSaveRequestIds.current[field] !== requestId) return;
      setFieldState(field, "saved");
      scheduleFieldReset(field, 1800);
    } catch (error) {
      if (fieldSaveRequestIds.current[field] !== requestId) return;
      setFieldState(field, "error");
      scheduleFieldReset(field, 3000);
      throw error;
    }
  }, [invalidateProject, lookupCompanyId, projectLookupRef, resolvedCompanyId, scheduleFieldReset, setFieldState]);

  // Redirect bare /projects/:id to /projects/:id/issues
  if (routeProjectRef && activeTab === null) {
    return <Navigate to={`/projects/${canonicalProjectRef}/issues`} replace />;
  }

  if (isLoading) return <PageSkeleton variant="detail" />;
  if (error) return <p className="text-sm text-destructive">{error.message}</p>;
  if (!project) return null;

  const handleTabChange = (tab: ProjectTab) => {
    if (tab === "overview") {
      navigate(`/projects/${canonicalProjectRef}/overview`);
    } else if (tab === "configuration") {
      navigate(`/projects/${canonicalProjectRef}/configuration`);
    } else {
      navigate(`/projects/${canonicalProjectRef}/issues`);
    }
  };

  return (
    <div className="space-y-6">
      <div className="flex items-start gap-3">
        <div className="h-7 flex items-center">
          <ColorPicker
            currentColor={project.color ?? "#6366f1"}
            onSelect={(color) => updateProject.mutate({ color })}
          />
        </div>
        <InlineEditor
          value={project.name}
          onSave={(name) => updateProject.mutate({ name })}
          as="h2"
          className="text-xl font-bold"
        />
      </div>

      <Tabs value={activeTab ?? "list"} onValueChange={(value) => handleTabChange(value as ProjectTab)}>
        <PageTabBar
          items={[
            { value: "overview", label: "Overview" },
            { value: "list", label: "List" },
            { value: "configuration", label: "Configuration" },
          ]}
          align="start"
          value={activeTab ?? "list"}
          onValueChange={(value) => handleTabChange(value as ProjectTab)}
        />
      </Tabs>

      {activeTab === "overview" && (
        <OverviewContent
          project={project}
          onUpdate={(data) => updateProject.mutate(data)}
          imageUploadHandler={async (file) => {
            const asset = await uploadImage.mutateAsync(file);
            return asset.contentPath;
          }}
        />
      )}

      {activeTab === "list" && project?.id && resolvedCompanyId && (
        <ProjectIssuesList projectId={project.id} companyId={resolvedCompanyId} />
      )}

      {activeTab === "configuration" && (
        <div className="max-w-4xl">
          <ProjectProperties
            project={project}
            onUpdate={(data) => updateProject.mutate(data)}
            onFieldUpdate={updateProjectField}
            getFieldSaveState={(field) => fieldSaveStates[field] ?? "idle"}
          />
        </div>
      )}
    </div>
  );
}