import { useEffect, useMemo, useState } from "react";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import {
  archiveWorkflowDefinition,
  createWorkflowDefinition,
  fetchWorkflowDefinitions,
  publishWorkflowDefinition,
  updateWorkflowDefinition,
  type WorkflowDefinitionEditorModel,
} from "../api/workflowDefinitions";
import { PageHeader } from "../components/common/PageHeader";
import { Button } from "../components/ui/button";
import { Input } from "../components/ui/input";
import { Label } from "../components/ui/label";
import { toast } from "sonner";

const ENTITY_TYPES: WorkflowDefinitionEditorModel["entityType"][] = ["reimbursement", "leave", "purchase_request", "travel_request"];

type DraftStep = WorkflowDefinitionEditorModel["steps"][number];

function emptyStep(): DraftStep {
  return { id: `step_${Date.now()}`, name: "审批节点", assigneeRule: { type: "department_manager" } };
}

export function WorkflowDefinitionsPage() {
  const queryClient = useQueryClient();
  const [entityType, setEntityType] = useState<WorkflowDefinitionEditorModel["entityType"]>("leave");
  const [selectedId, setSelectedId] = useState("");
  const [name, setName] = useState("");
  const [notes, setNotes] = useState("");
  const [steps, setSteps] = useState<DraftStep[]>([emptyStep()]);

  const listQuery = useQuery({ queryKey: ["workflow-definitions"], queryFn: () => fetchWorkflowDefinitions() });
  const items = listQuery.data?.items ?? [];
  const scopedItems = useMemo(() => items.filter((item) => item.entityType === entityType), [items, entityType]);
  const selected = useMemo(() => scopedItems.find((item) => item.id === selectedId) ?? scopedItems[0] ?? null, [scopedItems, selectedId]);

  useEffect(() => {
    if (!selected) return;
    setSelectedId(selected.id);
    setName(selected.name);
    setNotes(selected.notes ?? "");
    setSteps(selected.steps.length ? selected.steps : [emptyStep()]);
  }, [selected?.id]);

  const refresh = () => queryClient.invalidateQueries({ queryKey: ["workflow-definitions"] });

  const createMutation = useMutation({
    mutationFn: () => createWorkflowDefinition({ entityType, name: name.trim() || `${entityType}-workflow`, notes, steps }),
    onSuccess: async ({ item }) => {
      setSelectedId(item.id);
      await refresh();
      toast.success("流程定义草稿已创建");
    },
  });

  const saveMutation = useMutation({
    mutationFn: (id: string) => updateWorkflowDefinition(id, { name, notes, steps }),
    onSuccess: async () => {
      await refresh();
      toast.success("流程定义已保存");
    },
  });

  const publishMutation = useMutation({
    mutationFn: publishWorkflowDefinition,
    onSuccess: async () => {
      await refresh();
      toast.success("流程定义已发布");
    },
  });

  const archiveMutation = useMutation({
    mutationFn: archiveWorkflowDefinition,
    onSuccess: async () => {
      await refresh();
      toast.success("流程定义已归档");
    },
  });

  return (
    <div className="space-y-6">
      <PageHeader title="流程定义" subtitle="线性流程的版本化治理；报销继续由审批规则投影。" />
      <div className="grid gap-6 xl:grid-cols-[220px,280px,1fr]">
        <div className="card-std space-y-3 p-6">
          <Label>业务域</Label>
          <select className="select-std" value={entityType} onChange={(event) => setEntityType(event.target.value as WorkflowDefinitionEditorModel["entityType"])}>
            {ENTITY_TYPES.map((item) => <option key={item} value={item}>{item}</option>)}
          </select>
          {entityType !== "reimbursement" ? <Button type="button" onClick={() => createMutation.mutate()}>创建草稿</Button> : null}
        </div>

        <div className="card-std space-y-3 p-6">
          <h3 className="text-base font-semibold text-zinc-900">版本列表</h3>
          <div className="space-y-2">
            {scopedItems.map((item) => (
              <button key={item.id} type="button" className={selected?.id === item.id ? "w-full rounded-lg border border-primary bg-primary/5 px-3 py-3 text-left" : "w-full rounded-lg border border-zinc-200 px-3 py-3 text-left hover:bg-zinc-50"} onClick={() => setSelectedId(item.id)}>
                <div className="font-medium text-zinc-900">v{item.version} · {item.name}</div>
                <div className="text-xs text-zinc-500">{item.status} · {item.source}</div>
              </button>
            ))}
            {!scopedItems.length ? <div className="text-sm text-zinc-500">当前实体暂无流程定义</div> : null}
          </div>
        </div>

        <div className="card-std space-y-4 p-6">
          {selected ? (
            <>
              <div className="flex flex-wrap items-center justify-between gap-3">
                <div>
                  <div className="text-xs text-zinc-500">{selected.source}</div>
                  <div className="text-lg font-semibold text-zinc-900">{selected.name}</div>
                </div>
                {selected.status !== "derived_readonly" ? (
                  <div className="flex gap-2">
                    <Button type="button" variant="secondary" onClick={() => saveMutation.mutate(selected.id)} disabled={selected.status !== "draft"}>保存</Button>
                    <Button type="button" onClick={() => publishMutation.mutate(selected.id)} disabled={selected.status === "archived"}>发布</Button>
                    <Button type="button" variant="secondary" onClick={() => archiveMutation.mutate(selected.id)} disabled={selected.status === "archived"}>归档</Button>
                  </div>
                ) : null}
              </div>

              <div className="grid gap-4 md:grid-cols-2">
                <div className="space-y-2">
                  <Label>名称</Label>
                  <Input value={name} onChange={(event) => setName(event.target.value)} disabled={selected.status !== "draft"} />
                </div>
                <div className="space-y-2">
                  <Label>备注</Label>
                  <Input value={notes} onChange={(event) => setNotes(event.target.value)} disabled={selected.status !== "draft"} />
                </div>
              </div>

              <div className="space-y-3">
                <div className="flex items-center justify-between">
                  <h3 className="text-base font-semibold text-zinc-900">步骤</h3>
                  {selected.status === "draft" ? <Button type="button" variant="secondary" onClick={() => setSteps((prev) => [...prev, emptyStep()])}>新增步骤</Button> : null}
                </div>
                <div className="space-y-3">
                  {steps.map((step, index) => (
                    <div key={step.id} className="rounded-lg border border-zinc-200 p-4">
                      <div className="grid gap-3 md:grid-cols-3">
                        <Input value={step.id} disabled={selected.status !== "draft"} onChange={(event) => setSteps((prev) => prev.map((item, itemIndex) => itemIndex === index ? { ...item, id: event.target.value } : item))} />
                        <Input value={step.name} disabled={selected.status !== "draft"} onChange={(event) => setSteps((prev) => prev.map((item, itemIndex) => itemIndex === index ? { ...item, name: event.target.value } : item))} />
                        <select className="select-std" value={step.assigneeRule.type} disabled={selected.status !== "draft"} onChange={(event) => setSteps((prev) => prev.map((item, itemIndex) => itemIndex === index ? { ...item, assigneeRule: event.target.value === "role" ? { type: "role", value: "manager" } : event.target.value === "specific_user" ? { type: "specific_user", value: "" } : { type: "department_manager" } } : item))}>
                          <option value="department_manager">department_manager</option>
                          <option value="role">role</option>
                          <option value="specific_user">specific_user</option>
                        </select>
                      </div>
                      {step.assigneeRule.type !== "department_manager" ? (
                        <div className="mt-3">
                          <Input value={step.assigneeRule.value} disabled={selected.status !== "draft"} onChange={(event) => setSteps((prev) => prev.map((item, itemIndex) => itemIndex === index ? { ...item, assigneeRule: { ...item.assigneeRule, value: event.target.value } as DraftStep["assigneeRule"] } : item))} placeholder={step.assigneeRule.type === "role" ? "角色编码" : "用户 ID"} />
                        </div>
                      ) : null}
                    </div>
                  ))}
                </div>
              </div>
            </>
          ) : (
            <div className="text-sm text-zinc-500">暂无可编辑流程定义</div>
          )}
        </div>
      </div>
    </div>
  );
}