"use strict";

const fs = require("fs");
const fsp = fs.promises;
const path = require("path");

const STATUS_SET = new Set(["pending", "in-progress", "completed", "bug"]);
const NODE_TYPE_SET = new Set([
  "prompt",
  "sub-goal",
  "thought",
  "action",
  "observation",
  "conclusion",
]);
const EDGE_TYPE_SET = new Set(["hierarchy", "dependency", "reference", "merge"]);

function nowIso() {
  return new Date().toISOString();
}

function toStringSafe(value, maxLength) {
  if (value === undefined || value === null) return "";
  return String(value).trim().slice(0, maxLength);
}

function toNullableString(value, maxLength) {
  if (value === undefined || value === null || value === "") return null;
  const next = String(value).trim().slice(0, maxLength);
  return next || null;
}

function isValidIso(value) {
  if (value === null || value === undefined || value === "") return false;
  return Number.isFinite(Date.parse(String(value)));
}

function normalizeIso(value, fallback = null) {
  if (value === null || value === undefined || value === "") return fallback;
  const iso = String(value).trim();
  return isValidIso(iso) ? new Date(iso).toISOString() : fallback;
}

function normalizeStatus(value) {
  return STATUS_SET.has(value) ? value : "pending";
}

function normalizeNodeType(value, hasParent) {
  if (NODE_TYPE_SET.has(value)) return value;
  return hasParent ? "thought" : "prompt";
}

function createId(prefix = "node") {
  const rand = Math.random().toString(36).slice(2, 8);
  return `${prefix}-${Date.now()}-${rand}`;
}

function extractSessionKey(notes) {
  if (!notes) return null;
  const text = String(notes);
  const match = text.match(/sessionKey=([^\n\r]+)/);
  return match && match[1] ? match[1].trim() : null;
}

function extractContentFromNotes(notes) {
  if (!notes) return "";
  const text = String(notes);
  const match = text.match(/(?:^|\n)content=([^\n]+)/);
  if (match && match[1]) return match[1].trim().slice(0, 5000);
  return "";
}

function normalizeDiagnostics(input) {
  const source = input && typeof input === "object" ? input : {};
  const tokenUsage = source.tokenUsage && typeof source.tokenUsage === "object" ? source.tokenUsage : {};
  const stopReason = toNullableString(source.stopReason, 32);
  return {
    rawInputLength: Number.isFinite(source.rawInputLength) ? Math.max(0, Math.floor(source.rawInputLength)) : null,
    tokenUsage: {
      promptTokens: Number.isFinite(tokenUsage.promptTokens) ? Math.max(0, Math.floor(tokenUsage.promptTokens)) : null,
      completionTokens: Number.isFinite(tokenUsage.completionTokens)
        ? Math.max(0, Math.floor(tokenUsage.completionTokens))
        : null,
      totalTokens: Number.isFinite(tokenUsage.totalTokens) ? Math.max(0, Math.floor(tokenUsage.totalTokens)) : null,
    },
    stopReason,
    latencyMs: Number.isFinite(source.latencyMs) ? Math.max(0, Math.floor(source.latencyMs)) : null,
  };
}

function normalizeNode(input, fallback = {}) {
  const parentId = toNullableString(input.parentId, 180);
  const created = normalizeIso(input?.timestamps?.created || input.createdAt, nowIso());
  const started = normalizeIso(input?.timestamps?.started || input.startTime, null);
  const completed = normalizeIso(input?.timestamps?.completed || input.endTime, null);
  const updated = normalizeIso(input.updatedAt, nowIso());

  const status = normalizeStatus(input.status);
  const node = {
    id: toStringSafe(input.id || fallback.id || createId("task"), 180),
    conversationId: toNullableString(input.conversationId || fallback.conversationId, 240),
    parentId,
    nodeType: normalizeNodeType(input.nodeType || fallback.nodeType, Boolean(parentId)),
    name: toStringSafe(input.name || fallback.name || "未命名节点", 200) || "未命名节点",
    status,
    content: toStringSafe(input.content || fallback.content, 5000),
    timestamps: {
      created,
      started,
      completed,
    },
    llmDiagnostics: normalizeDiagnostics(input.llmDiagnostics || fallback.llmDiagnostics),
    plannedApproach: toStringSafe(input.plannedApproach || fallback.plannedApproach, 5000),
    bugDetails: toStringSafe(input.bugDetails || fallback.bugDetails, 5000),
    notes: toStringSafe(input.notes || fallback.notes, 8000),
    createdAt: created,
    updatedAt: updated,
  };

  if (node.status === "in-progress" && !node.timestamps.started) {
    node.timestamps.started = nowIso();
  }
  if ((node.status === "completed" || node.status === "bug") && !node.timestamps.completed) {
    node.timestamps.completed = nowIso();
  }

  return node;
}

function normalizeEdge(input) {
  const type = EDGE_TYPE_SET.has(input.type) ? input.type : "reference";
  return {
    id: toStringSafe(input.id || createId("edge"), 180),
    from: toStringSafe(input.from, 180),
    to: toStringSafe(input.to, 180),
    type,
    createdAt: normalizeIso(input.createdAt, nowIso()),
  };
}

function topologicalConversationPropagation(nodes) {
  const byId = new Map(nodes.map((node) => [node.id, node]));

  for (let i = 0; i < nodes.length + 2; i += 1) {
    let changed = false;
    for (const node of nodes) {
      if (node.conversationId) continue;
      if (!node.parentId) continue;
      const parent = byId.get(node.parentId);
      if (parent && parent.conversationId) {
        node.conversationId = parent.conversationId;
        changed = true;
      }
    }
    if (!changed) break;
  }

  for (const node of nodes) {
    if (!node.conversationId && !node.parentId) {
      node.conversationId = `legacy:${node.id}`;
    }
  }

  for (let i = 0; i < nodes.length + 2; i += 1) {
    let changed = false;
    for (const node of nodes) {
      if (node.conversationId) continue;
      if (!node.parentId) continue;
      const parent = byId.get(node.parentId);
      if (parent && parent.conversationId) {
        node.conversationId = parent.conversationId;
        changed = true;
      }
    }
    if (!changed) break;
  }

  for (const node of nodes) {
    if (!node.conversationId) {
      node.conversationId = `legacy:${node.id}`;
    }
  }
}

function migrateLegacyArray(tasks) {
  const nodes = tasks.map((item) => {
    const hasParent = Boolean(item.parentId);
    return normalizeNode(
      {
        id: item.id,
        conversationId: extractSessionKey(item.notes),
        parentId: item.parentId || null,
        nodeType: hasParent ? "thought" : "prompt",
        name: item.name,
        status: item.status,
        content: extractContentFromNotes(item.notes) || item.notes || "",
        timestamps: {
          created: item.createdAt,
          started: item.startTime,
          completed: item.endTime,
        },
        plannedApproach: item.plannedApproach,
        bugDetails: item.bugDetails,
        notes: item.notes,
        updatedAt: item.updatedAt,
      },
      {},
    );
  });

  topologicalConversationPropagation(nodes);

  const nodeSet = new Set(nodes.map((node) => node.id));
  const edges = [];
  const dedup = new Set();
  for (const node of nodes) {
    if (!node.parentId) continue;
    if (!nodeSet.has(node.parentId)) {
      node.parentId = null;
      continue;
    }
    const key = `${node.parentId}->${node.id}:hierarchy`;
    if (dedup.has(key)) continue;
    dedup.add(key);
    edges.push(
      normalizeEdge({
        from: node.parentId,
        to: node.id,
        type: "hierarchy",
      }),
    );
  }

  return {
    version: 2,
    updatedAt: nowIso(),
    nodes,
    edges,
  };
}

function normalizeStore(raw) {
  if (Array.isArray(raw)) {
    return migrateLegacyArray(raw);
  }

  const source = raw && typeof raw === "object" ? raw : {};
  const nodes = Array.isArray(source.nodes) ? source.nodes.map((item) => normalizeNode(item, item)) : [];
  const edgesRaw = Array.isArray(source.edges) ? source.edges : [];
  const nodeSet = new Set(nodes.map((node) => node.id));
  const edges = [];
  const dedup = new Set();

  for (const edge of edgesRaw) {
    const next = normalizeEdge(edge);
    if (!next.from || !next.to || next.from === next.to) continue;
    if (!nodeSet.has(next.from) || !nodeSet.has(next.to)) continue;
    const key = `${next.from}->${next.to}:${next.type}`;
    if (dedup.has(key)) continue;
    dedup.add(key);
    edges.push(next);
  }

  for (const node of nodes) {
    if (!node.parentId) continue;
    if (!nodeSet.has(node.parentId)) {
      node.parentId = null;
      continue;
    }
    const key = `${node.parentId}->${node.id}:hierarchy`;
    if (dedup.has(key)) continue;
    dedup.add(key);
    edges.push(
      normalizeEdge({
        from: node.parentId,
        to: node.id,
        type: "hierarchy",
      }),
    );
  }

  topologicalConversationPropagation(nodes);

  return {
    version: 2,
    updatedAt: normalizeIso(source.updatedAt, nowIso()),
    nodes,
    edges,
  };
}

function buildHierarchyMaps(store) {
  const children = new Map();
  const incomingHierarchy = new Map();
  for (const edge of store.edges) {
    if (edge.type !== "hierarchy") continue;
    if (!children.has(edge.from)) children.set(edge.from, []);
    children.get(edge.from).push(edge.to);
    incomingHierarchy.set(edge.to, edge.from);
  }
  return { children, incomingHierarchy };
}

class TaskRepository {
  constructor(options = {}) {
    this.filePath = options.filePath;
    this._mutationQueue = Promise.resolve();
  }

  async ensureFile() {
    const dir = path.dirname(this.filePath);
    await fsp.mkdir(dir, { recursive: true });
    if (!fs.existsSync(this.filePath)) {
      const initial = normalizeStore({ version: 2, nodes: [], edges: [] });
      await this.writeStore(initial);
    }
  }

  async readStore() {
    await this.ensureFile();
    try {
      const raw = await fsp.readFile(this.filePath, "utf8");
      const parsed = JSON.parse(raw);
      const normalized = normalizeStore(parsed);
      return normalized;
    } catch {
      return normalizeStore({ version: 2, nodes: [], edges: [] });
    }
  }

  async writeStore(store) {
    const normalized = normalizeStore(store);
    normalized.updatedAt = nowIso();
    const tmpPath = `${this.filePath}.${process.pid}.${Date.now()}.tmp`;
    await fsp.writeFile(tmpPath, `${JSON.stringify(normalized, null, 2)}\n`, "utf8");
    await fsp.rename(tmpPath, this.filePath);
    return normalized;
  }

  async mutate(mutator) {
    this._mutationQueue = this._mutationQueue.then(async () => {
      const store = await this.readStore();
      const result = await mutator(store);
      const nextStore = await this.writeStore(store);
      return { result, store: nextStore };
    });
    return this._mutationQueue;
  }

  async listConversations() {
    const store = await this.readStore();
    const { incomingHierarchy } = buildHierarchyMaps(store);
    const groups = new Map();

    for (const node of store.nodes) {
      if (!groups.has(node.conversationId)) {
        groups.set(node.conversationId, []);
      }
      groups.get(node.conversationId).push(node);
    }

    const summaries = [];
    for (const [conversationId, nodes] of groups.entries()) {
      const nodeIds = new Set(nodes.map((node) => node.id));
      const roots = nodes.filter((node) => !incomingHierarchy.has(node.id) || !nodeIds.has(incomingHierarchy.get(node.id)));
      const titleRoot = roots
        .slice()
        .sort((a, b) => (Date.parse(a.timestamps.created) || 0) - (Date.parse(b.timestamps.created) || 0))[0];
      const updatedAt = nodes.reduce((max, node) => {
        const t = Date.parse(node.updatedAt || node.timestamps.created || "") || 0;
        return Math.max(max, t);
      }, 0);
      const runningCount = nodes.filter((node) => node.status === "in-progress").length;
      const bugCount = nodes.filter((node) => node.status === "bug").length;
      summaries.push({
        conversationId,
        title: titleRoot ? titleRoot.name : conversationId,
        updatedAt: updatedAt ? new Date(updatedAt).toISOString() : nowIso(),
        nodeCount: nodes.length,
        runningCount,
        bugCount,
      });
    }

    summaries.sort((a, b) => (Date.parse(b.updatedAt) || 0) - (Date.parse(a.updatedAt) || 0));
    return summaries;
  }

  async getConversationGraph(conversationId) {
    const store = await this.readStore();
    const nodes = store.nodes.filter((node) => node.conversationId === conversationId);
    const nodeSet = new Set(nodes.map((node) => node.id));
    const edges = store.edges.filter((edge) => nodeSet.has(edge.from) && nodeSet.has(edge.to));

    return {
      conversationId,
      nodes,
      edges,
      summary: {
        nodeCount: nodes.length,
        edgeCount: edges.length,
        runningCount: nodes.filter((node) => node.status === "in-progress").length,
        bugCount: nodes.filter((node) => node.status === "bug").length,
      },
    };
  }

  async getNodeById(id) {
    const store = await this.readStore();
    return store.nodes.find((node) => node.id === id) || null;
  }

  async upsertNode(input) {
    return this.mutate(async (store) => {
      const index = store.nodes.findIndex((node) => node.id === input.id);
      const existing = index >= 0 ? store.nodes[index] : null;
      const merged = normalizeNode(input, existing || {});
      const byId = new Map(store.nodes.map((node) => [node.id, node]));

      if (existing && merged.id !== existing.id) {
        throw new Error("不允许变更节点 ID");
      }
      if (merged.parentId && merged.parentId === merged.id) {
        throw new Error("父节点不能是自己");
      }
      if (merged.parentId && !byId.has(merged.parentId)) {
        throw new Error("父节点不存在");
      }

      if (!merged.conversationId) {
        if (merged.parentId && byId.get(merged.parentId)) {
          merged.conversationId = byId.get(merged.parentId).conversationId;
        } else {
          merged.conversationId = `legacy:${merged.id}`;
        }
      }
      merged.updatedAt = nowIso();

      if (index >= 0) {
        store.nodes[index] = merged;
      } else {
        store.nodes.push(merged);
      }

      const nodeSet = new Set(store.nodes.map((node) => node.id));
      store.edges = store.edges.filter((edge) => nodeSet.has(edge.from) && nodeSet.has(edge.to));
      store.edges = store.edges.filter((edge) => !(edge.type === "hierarchy" && edge.to === merged.id));
      if (merged.parentId) {
        store.edges.push(
          normalizeEdge({
            from: merged.parentId,
            to: merged.id,
            type: "hierarchy",
          }),
        );
      }

      return merged;
    });
  }

  async deleteNode(id) {
    return this.mutate(async (store) => {
      const nodeIds = new Set(store.nodes.map((node) => node.id));
      if (!nodeIds.has(id)) {
        throw new Error("节点不存在");
      }

      const children = new Map();
      for (const edge of store.edges) {
        if (edge.type !== "hierarchy") continue;
        if (!children.has(edge.from)) children.set(edge.from, []);
        children.get(edge.from).push(edge.to);
      }

      const deleting = new Set([id]);
      const stack = [id];
      while (stack.length) {
        const current = stack.pop();
        const nextChildren = children.get(current) || [];
        for (const childId of nextChildren) {
          if (deleting.has(childId)) continue;
          deleting.add(childId);
          stack.push(childId);
        }
      }

      store.nodes = store.nodes.filter((node) => !deleting.has(node.id));
      store.edges = store.edges.filter((edge) => !deleting.has(edge.from) && !deleting.has(edge.to));
      return { deletedCount: deleting.size };
    });
  }

  async upsertEdge(input) {
    return this.mutate(async (store) => {
      const edge = normalizeEdge(input);
      if (!edge.from || !edge.to) {
        throw new Error("边的 from/to 不能为空");
      }
      if (edge.from === edge.to) {
        throw new Error("边不能自环");
      }

      const nodeSet = new Set(store.nodes.map((node) => node.id));
      if (!nodeSet.has(edge.from) || !nodeSet.has(edge.to)) {
        throw new Error("边关联的节点不存在");
      }

      const exists = store.edges.find((item) => item.from === edge.from && item.to === edge.to && item.type === edge.type);
      if (exists) return exists;
      store.edges.push(edge);
      return edge;
    });
  }

  async deleteEdge(params) {
    return this.mutate(async (store) => {
      const from = toStringSafe(params.from, 180);
      const to = toStringSafe(params.to, 180);
      const type = params.type ? toStringSafe(params.type, 48) : null;
      const before = store.edges.length;
      store.edges = store.edges.filter((edge) => {
        if (edge.from !== from || edge.to !== to) return true;
        if (type && edge.type !== type) return true;
        return false;
      });
      return { deletedCount: before - store.edges.length };
    });
  }
}

module.exports = {
  TaskRepository,
  STATUS_SET,
  NODE_TYPE_SET,
  EDGE_TYPE_SET,
  createId,
};