import { NextRequest, NextResponse } from 'next/server';
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { WebStandardStreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/webStandardStreamableHttp.js';
import { z } from 'zod';

export const runtime = 'nodejs';
export const maxDuration = 30;

const SERVER_INFO = {
  name: 'ra-h-mcp',
  version: '1.0.0',
};

const instructions = [
  'RA-H is a personal knowledge graph — local-first, vendor-neutral.',
  'Core concepts: contexts (optional soft scopes, max 10), nodes (knowledge units), and edges (connections with explanations).',
  'Always call rah_get_context first to orient yourself — it returns high-level graph state, contexts, hub nodes, stats, and available guides.',
  'Use contexts only when one obvious existing context is explicit and helpful. If unsure or if none exist, leave context empty. Do not expect automatic context assignment.',
  'Search before creating: use rah_search_nodes to check if content already exists.',
  'Every edge needs an explanation: why does this connection exist?',
].join(' ');

function getBaseUrl(request: NextRequest): string {
  const envBase = process.env.RAH_MCP_TARGET_URL || process.env.NEXT_PUBLIC_BASE_URL;
  return (envBase || request.nextUrl.origin).replace(/\/+$/, '');
}

async function callRaHApi(request: NextRequest, pathname: string, options: RequestInit = {}) {
  const response = await fetch(`${getBaseUrl(request)}${pathname}`, {
    ...options,
    headers: {
      'Content-Type': 'application/json',
      ...(options.headers || {}),
    },
  });

  const payload = await response.json().catch(() => null);
  if (!response.ok || !payload || payload.success === false) {
    throw new Error(payload?.error || `RA-H API request failed at ${pathname}`);
  }

  return payload;
}

function createServer(request: NextRequest): McpServer {
  const server = new McpServer(SERVER_INFO, {
    instructions,
    capabilities: { tools: {} },
  });

  server.registerTool(
    'rah_add_node',
    {
      title: 'Add RA-H node',
      description: 'Create a new node in the local RA-H knowledge base. Set context only when one obvious existing context clearly fits; otherwise leave it empty.',
      inputSchema: {
        title: z.string().min(1).max(160),
        content: z.string().max(20000).optional(),
        source: z.string().max(50000).optional(),
        link: z.string().url().optional(),
        description: z.string().max(500).optional(),
        context_id: z.number().int().positive().nullable().optional(),
        context_name: z.string().optional(),
        metadata: z.record(z.any()).optional(),
        chunk: z.string().max(50000).optional(),
      },
    },
    async ({ title, content, source, link, description, context_id, context_name, metadata, chunk }) => {
      const payload = await callRaHApi(request, '/api/nodes', {
        method: 'POST',
        body: JSON.stringify({
          title: title.trim(),
          source: source?.trim() || content?.trim() || chunk?.trim() || undefined,
          link: link?.trim() || undefined,
          description: description?.trim() || undefined,
          context_id,
          context_name: context_name?.trim() || undefined,
          metadata: metadata || {},
        }),
      });

      const node = payload.data;
      return {
        content: [{ type: 'text', text: `Created node #${node.id}: ${node.title}` }],
        structuredContent: {
          nodeId: node.id,
          title: node.title,
          message: payload.message || `Created node #${node.id}: ${node.title}`,
        },
      };
    }
  );

  server.registerTool(
    'rah_search_nodes',
    {
      title: 'Search RA-H nodes',
      description: 'Find existing RA-H entries that mention a topic before adding new ones.',
      inputSchema: {
        query: z.string().min(1).max(400),
        limit: z.number().min(1).max(25).optional(),
        contextId: z.number().int().positive().optional(),
      },
    },
    async ({ query, limit = 10, contextId }) => {
      const params = new URLSearchParams();
      params.set('search', query.trim());
      params.set('limit', String(Math.min(Math.max(limit, 1), 25)));
      if (contextId) params.set('contextId', String(contextId));

      const payload = await callRaHApi(request, `/api/nodes?${params.toString()}`);
      const nodes = Array.isArray(payload.data) ? payload.data : [];

      return {
        content: [{ type: 'text', text: nodes.length === 0 ? 'No existing RA-H nodes mention that topic yet.' : `Found ${nodes.length} node(s) mentioning that topic.` }],
        structuredContent: {
          count: nodes.length,
          nodes: nodes.map((node: any) => ({
            id: node.id,
            title: node.title,
            source: node.source ?? null,
            description: node.description ?? null,
            link: node.link ?? null,
            updated_at: node.updated_at,
          })),
        },
      };
    }
  );

  server.registerTool(
    'rah_query_contexts',
    {
      title: 'Query RA-H contexts',
      description: 'List or inspect optional contexts. Use this only when a context is already obviously relevant or the user asks for it.',
      inputSchema: {
        contextId: z.number().int().positive().optional(),
        name: z.string().optional(),
        search: z.string().optional(),
        limit: z.number().min(1).max(100).optional(),
        includeNodes: z.boolean().optional(),
      },
    },
    async ({ contextId, name, search, limit = 50, includeNodes = false }) => {
      const normalizedName = typeof name === 'string' ? name.trim().toLowerCase() : '';
      const normalizedSearch = typeof search === 'string' ? search.trim().toLowerCase() : '';

      let contexts: any[] = [];
      if (contextId) {
        const payload = await callRaHApi(request, `/api/contexts/${contextId}`);
        contexts = payload.data ? [payload.data] : [];
      } else {
        const payload = await callRaHApi(request, '/api/contexts');
        contexts = Array.isArray(payload.data) ? payload.data : [];
      }

      if (normalizedName) {
        contexts = contexts.filter((context) => context.name.toLowerCase() === normalizedName);
      }

      if (normalizedSearch) {
        contexts = contexts.filter((context) =>
          context.name.toLowerCase().includes(normalizedSearch) ||
          (context.description || '').toLowerCase().includes(normalizedSearch)
        );
      }

      contexts = contexts.slice(0, Math.min(Math.max(limit, 1), 100));

      const structuredContexts = await Promise.all(
        contexts.map(async (context) => {
          if (!(includeNodes && contexts.length === 1)) {
            return {
              id: context.id,
              name: context.name,
              description: context.description ?? null,
              icon: context.icon ?? null,
              count: context.count ?? 0,
            };
          }

          const nodesPayload = await callRaHApi(request, `/api/contexts/${context.id}/nodes`);
          const nodes = Array.isArray(nodesPayload.data) ? nodesPayload.data : [];

          return {
            id: context.id,
            name: context.name,
            description: context.description ?? null,
            icon: context.icon ?? null,
            count: context.count ?? nodes.length,
            nodes: nodes.map((node: any) => ({
              id: node.id,
              title: node.title,
              description: node.description ?? null,
              link: node.link ?? null,
              context_id: node.context_id ?? null,
              updated_at: node.updated_at,
            })),
          };
        })
      );

      return {
        content: [{ type: 'text', text: structuredContexts.length === 0 ? 'No contexts found.' : `Found ${structuredContexts.length} context(s).` }],
        structuredContent: {
          count: structuredContexts.length,
          contexts: structuredContexts,
        },
      };
    }
  );

  server.registerTool(
    'rah_update_node',
    {
      title: 'Update RA-H node',
      description: 'Update an existing node. Context remains optional and explicit.',
      inputSchema: {
        id: z.number().int().positive(),
        updates: z.object({
          title: z.string().optional(),
          description: z.string().max(500).optional(),
          content: z.string().optional(),
          source: z.string().optional(),
          link: z.string().optional(),
          context_id: z.number().int().positive().nullable().optional(),
          metadata: z.record(z.any()).optional(),
        }),
      },
    },
    async ({ id, updates }) => {
      const mappedUpdates = { ...updates } as Record<string, unknown>;
      if (mappedUpdates.content !== undefined && mappedUpdates.source === undefined) {
        mappedUpdates.source = mappedUpdates.content;
      }
      delete mappedUpdates.content;

      const payload = await callRaHApi(request, `/api/nodes/${id}`, {
        method: 'PUT',
        body: JSON.stringify(mappedUpdates),
      });

      return {
        content: [{ type: 'text', text: `Updated node #${id}` }],
        structuredContent: {
          success: true,
          nodeId: payload.node?.id || id,
          message: payload.message || `Updated node #${id}`,
        },
      };
    }
  );

  server.registerTool(
    'rah_get_nodes',
    {
      title: 'Get RA-H nodes by ID',
      description: 'Load full node records by their IDs.',
      inputSchema: {
        nodeIds: z.array(z.number().int().positive()).min(1).max(10),
      },
    },
    async ({ nodeIds }) => {
      const uniqueIds = Array.from(new Set(nodeIds.filter((id) => Number.isFinite(id) && id > 0)));
      const nodes: any[] = [];

      for (const id of uniqueIds) {
        try {
          const payload = await callRaHApi(request, `/api/nodes/${id}`);
          if (payload.node) {
            nodes.push({
              id: payload.node.id,
              title: payload.node.title,
              source: payload.node.source ?? null,
              link: payload.node.link ?? null,
              updated_at: payload.node.updated_at,
            });
          }
        } catch {
          // Skip missing nodes.
        }
      }

      return {
        content: [{ type: 'text', text: `Loaded ${nodes.length} of ${uniqueIds.length} nodes.` }],
        structuredContent: {
          count: nodes.length,
          nodes,
        },
      };
    }
  );

  server.registerTool(
    'rah_create_edge',
    {
      title: 'Create RA-H edge',
      description: 'Create a connection between two nodes.',
      inputSchema: {
        sourceId: z.number().int().positive(),
        targetId: z.number().int().positive(),
        explanation: z.string().min(1),
      },
    },
    async ({ sourceId, targetId, explanation }) => {
      const payload = await callRaHApi(request, '/api/edges', {
        method: 'POST',
        body: JSON.stringify({
          from_node_id: sourceId,
          to_node_id: targetId,
          explanation: explanation.trim(),
          source: 'helper_name',
          created_via: 'mcp',
        }),
      });

      const edge = payload.edge || payload.data;
      return {
        content: [{ type: 'text', text: `Created edge from #${sourceId} to #${targetId}` }],
        structuredContent: {
          success: true,
          edgeId: edge?.id || 0,
          message: payload.message || `Created edge from #${sourceId} to #${targetId}`,
        },
      };
    }
  );

  server.registerTool(
    'rah_query_edges',
    {
      title: 'Query RA-H edges',
      description: 'Find connections between nodes.',
      inputSchema: {
        nodeId: z.number().int().positive().optional(),
        limit: z.number().min(1).max(50).optional(),
      },
    },
    async ({ nodeId, limit = 25 }) => {
      const params = new URLSearchParams();
      if (nodeId) params.set('nodeId', String(nodeId));
      params.set('limit', String(Math.min(Math.max(limit, 1), 50)));

      const payload = await callRaHApi(request, `/api/edges?${params.toString()}`);
      const edges = Array.isArray(payload.data) ? payload.data : [];

      return {
        content: [{ type: 'text', text: `Found ${edges.length} edge(s).` }],
        structuredContent: {
          count: edges.length,
          edges: edges.map((edge: any) => ({
            id: edge.id,
            source_id: edge.from_node_id,
            target_id: edge.to_node_id,
            type: edge.context?.type ?? null,
            weight: typeof edge.context?.confidence === 'number' ? edge.context.confidence : null,
          })),
        },
      };
    }
  );

  server.registerTool(
    'rah_update_edge',
    {
      title: 'Update RA-H edge',
      description: 'Update an existing edge connection.',
      inputSchema: {
        id: z.number().int().positive(),
        explanation: z.string().min(1),
      },
    },
    async ({ id, explanation }) => {
      const payload = await callRaHApi(request, `/api/edges/${id}`, {
        method: 'PUT',
        body: JSON.stringify({
          context: { explanation: explanation.trim(), created_via: 'mcp' },
        }),
      });

      return {
        content: [{ type: 'text', text: `Updated edge #${id}` }],
        structuredContent: {
          success: true,
          message: payload.message || `Updated edge #${id}`,
        },
      };
    }
  );

  server.registerTool(
    'rah_search_embeddings',
    {
      title: 'Semantic search RA-H',
      description: 'Search node content using semantic similarity.',
      inputSchema: {
        query: z.string().min(1),
        limit: z.number().min(1).max(20).optional(),
      },
    },
    async ({ query, limit = 10 }) => {
      const params = new URLSearchParams();
      params.set('q', query);
      params.set('limit', String(Math.min(Math.max(limit, 1), 20)));

      const payload = await callRaHApi(request, `/api/nodes/search?${params.toString()}`);
      const results = Array.isArray(payload.data) ? payload.data : [];

      return {
        content: [{ type: 'text', text: `Found ${results.length} semantically similar result(s).` }],
        structuredContent: {
          count: results.length,
          results: results.map((result: any) => ({
            nodeId: result.node_id || result.nodeId || result.id,
            title: result.title || 'Untitled',
            chunkPreview: (result.source || '').slice(0, 200),
            similarity: result.similarity || result.score || 0,
          })),
        },
      };
    }
  );

  server.registerTool(
    'rah_extract_url',
    {
      title: 'Extract URL content',
      description: 'Extract content from a webpage URL.',
      inputSchema: {
        url: z.string().url(),
      },
    },
    async ({ url }) => {
      const payload = await callRaHApi(request, '/api/extract/url', {
        method: 'POST',
        body: JSON.stringify({ url }),
      });

      return {
        content: [{ type: 'text', text: `Extracted content from: ${payload.title || 'webpage'}` }],
        structuredContent: {
          success: true,
          title: payload.title || 'Untitled',
          source: payload.source || '',
          metadata: payload.metadata || {},
        },
      };
    }
  );

  server.registerTool(
    'rah_extract_youtube',
    {
      title: 'Extract YouTube transcript',
      description: 'Extract transcript from a YouTube video.',
      inputSchema: {
        url: z.string(),
      },
    },
    async ({ url }) => {
      const payload = await callRaHApi(request, '/api/extract/youtube', {
        method: 'POST',
        body: JSON.stringify({ url }),
      });

      return {
        content: [{ type: 'text', text: `Extracted transcript from: ${payload.title || 'YouTube video'}` }],
        structuredContent: {
          success: true,
          title: payload.title || 'Untitled',
          channel: payload.channel || 'Unknown',
          source: payload.source || '',
          metadata: payload.metadata || {},
        },
      };
    }
  );

  server.registerTool(
    'rah_extract_pdf',
    {
      title: 'Extract PDF content',
      description: 'Extract content from a PDF file URL.',
      inputSchema: {
        url: z.string().url(),
      },
    },
    async ({ url }) => {
      const payload = await callRaHApi(request, '/api/extract/pdf', {
        method: 'POST',
        body: JSON.stringify({ url }),
      });

      return {
        content: [{ type: 'text', text: `Extracted content from: ${payload.title || 'PDF document'}` }],
        structuredContent: {
          success: true,
          title: payload.title || 'Untitled PDF',
          source: payload.source || '',
          metadata: payload.metadata || {},
        },
      };
    }
  );

  server.registerTool(
    'rah_get_context',
    {
      title: 'Get RA-H context',
      description: 'Get orientation context: high-level graph state, optional contexts, hub nodes, stats, and available guides.',
      inputSchema: {},
    },
    async () => {
      const [hubPayload, contextsPayload, guidesPayload, countPayload] = await Promise.all([
        callRaHApi(request, '/api/nodes?sortBy=edges&limit=5'),
        callRaHApi(request, '/api/contexts'),
        callRaHApi(request, '/api/guides').catch(() => ({ data: [] })),
        callRaHApi(request, '/api/nodes?limit=1').catch(() => ({ total: 0 })),
      ]);

      const hubNodes = Array.isArray(hubPayload.data) ? hubPayload.data.map((node: any) => ({
        id: node.id,
        title: node.title,
        description: node.description ?? null,
        edgeCount: node.edge_count ?? 0,
      })) : [];

      const contexts = Array.isArray(contextsPayload.data) ? contextsPayload.data.map((context: any) => ({
        id: context.id,
        name: context.name,
        description: context.description ?? null,
        icon: context.icon ?? null,
        count: context.count ?? 0,
      })) : [];

      const guides = Array.isArray(guidesPayload.data) ? guidesPayload.data.map((guide: any) => guide.name) : [];

      return {
        content: [{ type: 'text', text: `Knowledge graph: ${contexts.length} optional contexts, ${hubNodes.length} hub nodes, ${guides.length} guides available.` }],
        structuredContent: {
          stats: {
            nodeCount: countPayload.total ?? 0,
            edgeCount: 0,
            contextCount: contexts.length,
          },
          hubNodes,
          contexts,
          guides,
        },
      };
    }
  );

  return server;
}

export async function POST(request: NextRequest) {
  try {
    const server = createServer(request);
    const transport = new WebStandardStreamableHTTPServerTransport({
      sessionIdGenerator: undefined,
    });

    await server.connect(transport);
    const response = await transport.handleRequest(request);
    await transport.close();
    await server.close();

    return response;
  } catch (error) {
    console.error('MCP request error:', error);
    return NextResponse.json(
      {
        jsonrpc: '2.0',
        error: {
          code: -32603,
          message: error instanceof Error ? error.message : 'Internal MCP error',
        },
      },
      {
        status: 500,
        headers: {
          'Content-Type': 'application/json',
          'Access-Control-Allow-Origin': '*',
        },
      }
    );
  }
}

export async function OPTIONS() {
  return new NextResponse(null, {
    status: 204,
    headers: {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'GET, POST, OPTIONS',
      'Access-Control-Allow-Headers': 'Content-Type, Accept, Mcp-Session-Id',
    },
  });
}

export async function GET(request: NextRequest) {
  const tools = [
    'rah_add_node',
    'rah_search_nodes',
    'rah_query_contexts',
    'rah_update_node',
    'rah_get_nodes',
    'rah_create_edge',
    'rah_query_edges',
    'rah_update_edge',
    'rah_search_embeddings',
    'rah_extract_url',
    'rah_extract_youtube',
    'rah_extract_pdf',
    'rah_get_context',
  ];

  return NextResponse.json(
    {
      name: SERVER_INFO.name,
      version: SERVER_INFO.version,
      description: 'RA-H Knowledge Graph - Remote MCP Server',
      target: getBaseUrl(request),
      tools,
    },
    {
      headers: { 'Access-Control-Allow-Origin': '*' },
    }
  );
}