/**
 * process 用例 —— 流程引擎:确定性流转,**零 LLM、零临场**(编码规范 §5.3;语义出处 OS 03 / 04)。
 *
 * 起单 · 调度节点 · 审批点卡工位 · 网关分合 · 每次流转记入事件。
 */
import type { ProcessNode, ProcessPackage, StaffId, TerminalState, WorkflowState } from '@contracts';
import type { ProcessService, StartWorkflowInput } from '../../contract.ts';
import { NotPublishableError, PositionVacantError } from '../../contract.ts';
import type {
  ActivityDirectory,
  ApprovalGateway,
  Clock,
  FlowEventPublisher,
  IdGenerator,
  OrgDirectory,
  ProcessStore,
  ReceiptNotifier,
  Sfeel,
  TaskGateway,
  WorkflowRecord,
} from '../../port.ts';
import { checkClosure } from '../domain/closure.ts';
import { aggregateWorkflowState, isDigested, nextInstanceNumber, resolveOwner } from '../domain/owner-resolution.ts';
import type { NodeInstance } from '../domain/owner-resolution.ts';
import { assemble, dispatchOf, joinReady, rejectRouteOf, selectEdges, startNodeOf } from '../domain/routing.ts';

export type ProcessServiceDeps = {
  readonly store: ProcessStore;
  readonly activities: ActivityDirectory;
  readonly org: OrgDirectory;
  readonly tasks: TaskGateway;
  readonly approvals: ApprovalGateway;
  readonly sfeel: Sfeel;
  readonly events: FlowEventPublisher;
  readonly receipts: ReceiptNotifier;
  readonly clock: Clock;
  readonly ids: IdGenerator;
};

export function createProcessService(deps: ProcessServiceDeps): ProcessService {
  async function requirePackage(id: string, version?: number): Promise<ProcessPackage> {
    const pkg = await deps.store.getPackage(id, version);
    if (pkg === undefined) throw new Error(`流程包不存在:${id}`);
    return pkg;
  }

  async function requireWorkflow(id: string): Promise<WorkflowRecord> {
    const record = await deps.store.getWorkflow(id);
    if (record === undefined) throw new Error(`工作流不存在:${id}`);
    return record;
  }

  function scopeOf(record: WorkflowRecord) {
    return { ports: record.ports, vars: record.vars, initiation: record.initiation };
  }

  /** 起一个节点:活动 → 起单;审批点 → 卡工位;终点 → 收束 */
  async function enter(
    record: WorkflowRecord,
    pkg: ProcessPackage,
    node: ProcessNode,
    payload: Record<string, unknown>,
  ): Promise<void> {
    const dispatch = dispatchOf(node, payload);

    if (dispatch === undefined) {
      // 网关本身不是责任单元:直接继续流转
      await advanceFrom(record, pkg, node.id, payload);
      return;
    }

    const instances = await deps.store.listInstances(record.id);
    const instance = nextInstanceNumber(instances, node.id);

    if (dispatch.kind === 'finish') {
      await deps.store.insertInstance(record.id, {
        nodeId: node.id,
        instance,
        running: false,
        waiting: false,
        activated: true,
        terminal: 'released',
      });
      const finished = await deps.store.updateWorkflow(record.id, {
        state: 'completed',
        finishedAt: deps.clock.now().toISOString(),
        ports: { ...record.ports, __output: payload },
      });
      await deps.events.publish({ workflowId: record.id, kind: 'workflow-completed', detail: payload });
      // 凡单必有来源 —— 登记人收消息回执
      if (record.source.by !== undefined) {
        await deps.receipts.notify({
          to: record.source.by as StaffId,
          workflowId: record.id,
          subject: record.subject,
          state: finished.state,
        });
      }
      return;
    }

    // 负责人 / 审批人:编排声明岗位,起单时确定性解析;结果与依据留痕
    const spec = dispatch.kind === 'start-task' ? dispatch.node.owner : dispatch.node.approver;
    const candidates = await deps.org.candidates(spec.position);
    const resolution = resolveOwner(spec, { candidates });
    if (resolution.kind === 'vacant') throw new PositionVacantError(spec.position);

    await deps.events.publish({
      workflowId: record.id,
      kind: 'owner-resolved',
      detail: { nodeId: node.id, position: spec.position, staffId: resolution.staffId, by: resolution.by, rationale: resolution.rationale },
    });

    if (dispatch.kind === 'start-task') {
      const task = await deps.tasks.start({
        activityId: dispatch.node.activityId,
        ownerId: resolution.staffId as StaffId,
        title: dispatch.node.label,
        workflowId: record.id,
        nodeId: node.id,
        data: payload,
        ...(dispatch.node.message === undefined ? {} : { message: dispatch.node.message }),
      });
      await deps.store.insertInstance(record.id, {
        nodeId: node.id,
        instance,
        running: true,
        waiting: false,
        activated: true,
        taskId: task.id,
      });
      await deps.events.publish({ workflowId: record.id, kind: 'task-started', detail: { nodeId: node.id, taskId: task.id } });
      return;
    }

    const approval = await deps.approvals.raise({
      workflowId: record.id,
      nodeId: node.id,
      approverId: resolution.staffId as StaffId,
      subject: dispatch.node.label,
      basis: Object.entries(payload).map(([k, v]) => ({ k, v: String(v) })),
    });
    await deps.store.insertInstance(record.id, {
      nodeId: node.id,
      instance,
      running: false,
      waiting: true,
      activated: true,
      approvalId: approval.id,
    });
    await deps.events.publish({ workflowId: record.id, kind: 'approval-raised', detail: { nodeId: node.id, approvalId: approval.id } });
  }

  /** 从某节点继续流转:选边 → 装配 → 进下一节点(AND 汇合要回齐) */
  async function advanceFrom(
    record: WorkflowRecord,
    pkg: ProcessPackage,
    fromNodeId: string,
    payload: Record<string, unknown>,
  ): Promise<void> {
    const scope = scopeOf(record);
    const flat = { ...scope.initiation, ...scope.vars, ...payload };
    const edges = selectEdges(pkg, fromNodeId, flat, deps.sfeel.condition);

    for (const edge of edges) {
      const target = pkg.nodes.find((n) => n.id === edge.to);
      if (target === undefined) continue;

      if (target.kind === 'gateway' && target.mode === 'join') {
        const instances = await deps.store.listInstances(record.id);
        const converged = new Set(instances.filter((i) => i.terminal === 'released').map((i) => i.nodeId));
        const tolerated = new Set(instances.filter((i) => i.failureDigested === true).map((i) => i.nodeId));
        // 未回齐就等着 —— 别的分支到了会再来一次
        if (!joinReady(pkg, target.id, converged, tolerated)) continue;
      }

      const assembled = assemble(edge, { ...scope, ports: { ...scope.ports, [fromNodeId]: payload } }, deps.sfeel.expression);
      await enter(record, pkg, target, assembled);
    }
  }

  return {
    async savePackage(pkg) {
      await deps.store.savePackage(pkg);
      return pkg;
    },

    async listPackages() {
      return deps.store.listPackages();
    },

    async getPackage(id, version) {
      return deps.store.getPackage(id, version);
    },

    /** 画图即校验:发布前跑闭合校验 */
    async validate(pkg) {
      return checkClosure({
        pkg,
        contracts: await deps.activities.faces(),
        positions: await deps.org.positions(),
      });
    },

    /** 不闭合不得发布 */
    async publish(id, version) {
      const pkg = await requirePackage(id, version);
      const report = await this.validate(pkg);
      if (!report.publishable) throw new NotPublishableError(report);
      await deps.store.publishPackage(id, version);
      return report;
    },

    /** 起单:经调用接口调起流程包,生成一条工作流 */
    async start(input: StartWorkflowInput) {
      const pkg = await requirePackage(input.packageId, input.packageVersion);
      if (pkg.state !== 'published') throw new Error(`流程包未发布,不得起单:${pkg.id}@${pkg.version}`);

      const record: WorkflowRecord = {
        id: deps.ids.next(),
        packageId: pkg.id,
        packageVersion: pkg.version,
        subject: input.subject,
        state: 'running',
        source: input.source,
        initiation: input.data,
        ports: {},
        vars: {},
        startedAt: deps.clock.now().toISOString(),
      };
      await deps.store.insertWorkflow(record);
      await deps.events.publish({ workflowId: record.id, kind: 'workflow-started', detail: { source: input.source } });

      const start = startNodeOf(pkg);
      if (start !== undefined) await advanceFrom(record, pkg, start.id, input.data);
      return record;
    },

    async getWorkflow(id) {
      return requireWorkflow(id);
    },

    async listWorkflows(limit = 50) {
      return deps.store.listWorkflows(limit);
    },

    async instancesOf(workflowId) {
      return deps.store.listInstances(workflowId);
    },

    /** 任务终态到达:按终态决定继续流转还是走失败走向 */
    async onTaskTerminal(taskId, terminal: TerminalState, ports: Record<string, Record<string, unknown>>) {
      const located = await deps.store.findInstanceByTask(taskId);
      if (located === undefined) return undefined;

      const record = await requireWorkflow(located.workflowId);
      const pkg = await requirePackage(record.packageId, record.packageVersion);
      const node = pkg.nodes.find((n) => n.id === located.nodeId);

      await deps.store.updateInstance(record.id, located.nodeId, located.instance, {
        running: false,
        waiting: false,
        terminal,
      });
      await deps.events.publish({ workflowId: record.id, kind: 'task-terminal', detail: { taskId, terminal } });

      const merged = await deps.store.updateWorkflow(record.id, { ports: { ...record.ports, ...ports } });

      if (terminal === 'released') {
        // 落地收敛后才发射输出口 —— 下游只见落地完成的任务
        const payload = Object.values(ports)[0] ?? {};
        await advanceFrom(merged, pkg, located.nodeId, payload);
      } else if (node?.kind === 'activity') {
        // 非完成终态触发**声明的失败走向**;流程层不自动重试
        await this.applyFailure(record.id, located.nodeId, located.instance, node, terminal);
      }

      return this.refreshState(record.id);
    },

    /** 失败走向四选一:终止流(默认)/ 改道 / 升审批 / 容忍 */
    async applyFailure(workflowId, nodeId, instance, node, terminal) {
      const record = await requireWorkflow(workflowId);
      const pkg = await requirePackage(record.packageId, record.packageVersion);
      const disposition = node.failure;
      const digested = isDigested(disposition.kind);

      await deps.store.updateInstance(workflowId, nodeId, instance, { failureDigested: digested });
      await deps.events.publish({
        workflowId,
        kind: 'failure-disposition',
        detail: { nodeId, terminal, disposition: disposition.kind },
      });

      if (disposition.kind === 'reroute') {
        const edge = pkg.edges.find((e) => e.id === disposition.edgeId);
        const target = edge === undefined ? undefined : pkg.nodes.find((n) => n.id === edge.to);
        if (edge !== undefined && target !== undefined) {
          // 失败载荷 = 终态、原因码与说明
          const payload = assemble(edge, scopeOf(record), deps.sfeel.expression);
          await enter(record, pkg, target, { ...payload, __terminal: terminal });
        }
      }

      if (disposition.kind === 'escalate') {
        const target = pkg.nodes.find((n) => n.id === disposition.approvalNodeId);
        if (target !== undefined) await enter(record, pkg, target, { __terminal: terminal, __from: nodeId });
      }

      return this.refreshState(workflowId);
    },

    /** 审批裁决:通过继续流转;驳回按**声明的走向**回指定节点重开新实例 */
    async onApprovalVerdict(workflowId, nodeId, verdict, payload) {
      const record = await requireWorkflow(workflowId);
      const pkg = await requirePackage(record.packageId, record.packageVersion);
      const node = pkg.nodes.find((n) => n.id === nodeId);
      if (node?.kind !== 'approval') throw new Error(`节点不是审批点:${nodeId}`);

      const instances = await deps.store.listInstances(workflowId);
      const current = instances.filter((i) => i.nodeId === nodeId).at(-1);
      if (current !== undefined) {
        await deps.store.updateInstance(workflowId, nodeId, current.instance, {
          waiting: false,
          terminal: 'released',
        });
      }
      await deps.events.publish({ workflowId, kind: 'approval-verdict', detail: { nodeId, verdict } });

      if (verdict === 'pass') {
        await advanceFrom(record, pkg, nodeId, payload);
      } else {
        const route = rejectRouteOf(node, scopeOf(record), deps.sfeel.expression);
        if (route.kind === 'terminate') {
          await deps.store.updateWorkflow(workflowId, { state: 'terminated', finishedAt: deps.clock.now().toISOString() });
        } else {
          // 回指定节点**重开新实例**(同节点、新任务 ID、留痕关联),不复活旧任务
          const target = pkg.nodes.find((n) => n.id === route.nodeId);
          if (target !== undefined) await enter(record, pkg, target, { ...route.payload, ...payload });
        }
      }
      return this.refreshState(workflowId);
    },

    /** 工作流状态是聚合投影 —— 每次变动后重算 */
    async refreshState(workflowId): Promise<WorkflowState> {
      const record = await requireWorkflow(workflowId);
      if (record.state === 'terminated') return 'terminated';
      const instances = await deps.store.listInstances(workflowId);
      const state = aggregateWorkflowState(instances as NodeInstance[], false);
      if (state !== record.state) {
        await deps.store.updateWorkflow(workflowId, {
          state,
          ...(state === 'completed' ? { finishedAt: deps.clock.now().toISOString() } : {}),
        });
      }
      return state;
    },

    async terminate(workflowId, reason) {
      await deps.store.updateWorkflow(workflowId, {
        state: 'terminated',
        finishedAt: deps.clock.now().toISOString(),
      });
      // 工作流终止级联:在途任务终止、待答卡与征答消息作废、审批点撤卡
      await deps.events.publish({ workflowId, kind: 'workflow-terminated', detail: { reason } });
      return 'terminated';
    },
  };
}