import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
import { WaveClient } from "../services/wave-client.js";
import { WaveInvoice } from "../types.js";
import { DEFAULT_PAGE_SIZE, MAX_PAGE_SIZE } from "../constants.js";

interface InvoicesData {
  business: {
    invoices: {
      pageInfo: { currentPage: number; totalPages: number; totalCount: number };
      edges: Array<{ node: WaveInvoice }>;
    };
  };
}

interface InvoiceData {
  business: { invoice: WaveInvoice };
}

interface InvoiceCreateData {
  invoiceCreate: {
    didSucceed: boolean;
    inputErrors: Array<{ code: string; message: string; path: string[] }>;
    invoice?: WaveInvoice;
  };
}

interface InvoicePatchData {
  invoicePatch: {
    didSucceed: boolean;
    inputErrors: Array<{ code: string; message: string; path: string[] }>;
    invoice?: WaveInvoice;
  };
}

interface InvoiceActionData {
  invoiceApprove?: { didSucceed: boolean; inputErrors: Array<{ message: string }> };
  invoiceSend?: { didSucceed: boolean; inputErrors: Array<{ message: string }>; invoice?: { id: string } };
  invoiceMarkSent?: { didSucceed: boolean; inputErrors: Array<{ message: string }> };
  invoiceDelete?: { didSucceed: boolean; inputErrors: Array<{ message: string }> };
}

const INVOICE_FIELDS = `
  id pdfUrl viewUrl status title subhead invoiceNumber
  invoiceDate dueDate memo
  customer { id name email }
  currency { code }
  amountDue { value currency { code } }
  amountPaid { value currency { code } }
  taxTotal { value currency { code } }
  subtotal { value currency { code } }
  total { value currency { code } }
  items {
    product { id name }
    description quantity unitPrice subtotal total
    account { id name }
  }
  createdAt modifiedAt
`;

function formatInvoiceMarkdown(inv: WaveInvoice): string[] {
  const lines = [
    `## Invoice #${inv.invoiceNumber} — ${inv.customer?.name ?? "Unknown"} (${inv.id})`,
    `- **Status**: ${inv.status}`,
    `- **Date**: ${inv.invoiceDate ?? "N/A"}`,
    `- **Due**: ${inv.dueDate ?? "N/A"}`,
    `- **Total**: ${WaveClient.formatCurrency(inv.total?.value ?? 0, inv.currency?.code ?? "")}`,
    `- **Amount Due**: ${WaveClient.formatCurrency(inv.amountDue?.value ?? 0, inv.currency?.code ?? "")}`,
    `- **Amount Paid**: ${WaveClient.formatCurrency(inv.amountPaid?.value ?? 0, inv.currency?.code ?? "")}`,
  ];
  if (inv.pdfUrl) lines.push(`- **PDF**: ${inv.pdfUrl}`);
  if (inv.viewUrl) lines.push(`- **View**: ${inv.viewUrl}`);
  lines.push("");
  return lines;
}

export function registerInvoiceTools(server: McpServer, client: WaveClient): void {
  // ── wave_list_invoices ────────────────────────────────────────────────────

  server.registerTool(
    "wave_list_invoices",
    {
      title: "List Wave Invoices",
      description: `List invoices for a Wave business with optional filtering by status or customer.

Args:
  - businessId (string): Wave business ID
  - page (number): Page number (default: 1)
  - pageSize (number): Items per page, 1-100 (default: 20)
  - customerId (string): Filter by customer ID (optional)
  - invoiceNumber (string): Filter by invoice number (optional)
  - status ('DRAFT' | 'APPROVED' | 'SENT' | 'VIEWED' | 'PARTIALLY_PAID' | 'PAID' | 'OVERDUE'): Filter by status (optional)
  - response_format ('markdown' | 'json'): Output format (default: 'markdown')

Returns:
  Paginated list of invoices with totals, status, and customer info.`,
      inputSchema: z.object({
        businessId: z.string().describe("Wave business ID"),
        page: z.number().int().min(1).default(1).describe("Page number"),
        pageSize: z.number().int().min(1).max(MAX_PAGE_SIZE).default(DEFAULT_PAGE_SIZE).describe("Items per page"),
        customerId: z.string().optional().describe("Filter by customer ID"),
        invoiceNumber: z.string().optional().describe("Filter by invoice number"),
        status: z.enum(["DRAFT", "APPROVED", "SENT", "VIEWED", "PARTIALLY_PAID", "PAID", "OVERDUE"]).optional().describe("Filter by status"),
        response_format: z.enum(["markdown", "json"]).default("markdown").describe("Output format"),
      }),
      annotations: { readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: true },
    },
    async ({ businessId, page, pageSize, customerId, invoiceNumber, status, response_format }) => {
      try {
        // Build optional filter variables
        const vars: Record<string, unknown> = { businessId, page, pageSize };
        if (customerId) vars.customerId = customerId;
        if (invoiceNumber) vars.invoiceNumber = invoiceNumber;
        if (status) vars.status = status;

        const data = await client.query<InvoicesData>(`
          query($businessId: ID!, $page: Int!, $pageSize: Int!) {
            business(id: $businessId) {
              invoices(page: $page, pageSize: $pageSize) {
                pageInfo { currentPage totalPages totalCount }
                edges { node { ${INVOICE_FIELDS} } }
              }
            }
          }
        `, vars);

        let { pageInfo, edges } = data.business.invoices;
        let invoices = edges.map((e) => e.node);

        // Client-side filter since Wave API may not support all filter params at query level
        if (customerId) invoices = invoices.filter((i) => i.customer?.id === customerId);
        if (status) invoices = invoices.filter((i) => i.status === status);
        if (invoiceNumber) invoices = invoices.filter((i) => i.invoiceNumber?.includes(invoiceNumber));

        if (!invoices.length) {
          return { content: [{ type: "text", text: "No invoices found matching the criteria." }] };
        }

        const result = {
          total: pageInfo.totalCount,
          count: invoices.length,
          page: pageInfo.currentPage,
          totalPages: pageInfo.totalPages,
          has_more: pageInfo.currentPage < pageInfo.totalPages,
          next_page: pageInfo.currentPage < pageInfo.totalPages ? pageInfo.currentPage + 1 : undefined,
          invoices,
        };

        let text: string;
        if (response_format === "json") {
          text = JSON.stringify(result, null, 2);
        } else {
          const lines = [`# Invoices (${pageInfo.totalCount} total, page ${pageInfo.currentPage}/${pageInfo.totalPages})`, ""];
          for (const inv of invoices) lines.push(...formatInvoiceMarkdown(inv));
          text = lines.join("\n");
        }

        return {
          content: [{ type: "text", text: WaveClient.truncate(text) }],
          structuredContent: result,
        };
      } catch (error) {
        return { content: [{ type: "text", text: `Error: ${error instanceof Error ? error.message : String(error)}` }] };
      }
    }
  );

  // ── wave_get_invoice ──────────────────────────────────────────────────────

  server.registerTool(
    "wave_get_invoice",
    {
      title: "Get Wave Invoice",
      description: `Get full details for a specific invoice including line items.

Args:
  - businessId (string): Wave business ID
  - invoiceId (string): Invoice ID
  - response_format ('markdown' | 'json'): Output format (default: 'markdown')

Returns:
  Full invoice with all line items, totals, dates, and PDF/view links.`,
      inputSchema: z.object({
        businessId: z.string().describe("Wave business ID"),
        invoiceId: z.string().describe("Invoice ID"),
        response_format: z.enum(["markdown", "json"]).default("markdown").describe("Output format"),
      }),
      annotations: { readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: true },
    },
    async ({ businessId, invoiceId, response_format }) => {
      try {
        const data = await client.query<InvoiceData>(`
          query($businessId: ID!, $invoiceId: ID!) {
            business(id: $businessId) {
              invoice(id: $invoiceId) { ${INVOICE_FIELDS} }
            }
          }
        `, { businessId, invoiceId });

        const inv = data.business.invoice;
        if (!inv) return { content: [{ type: "text", text: `No invoice found with ID: ${invoiceId}` }] };

        let text: string;
        if (response_format === "json") {
          text = JSON.stringify(inv, null, 2);
        } else {
          const lines = [...formatInvoiceMarkdown(inv)];
          if (inv.items?.length) {
            lines.push("### Line Items", "");
            for (const item of inv.items) {
              const desc = item.description ?? item.product?.name ?? "Item";
              lines.push(`- ${desc}: ${item.quantity} × ${WaveClient.formatCurrency(item.unitPrice, inv.currency?.code ?? "")} = ${WaveClient.formatCurrency(item.total, inv.currency?.code ?? "")}`);
            }
          }
          text = lines.join("\n");
        }

        return { content: [{ type: "text", text }], structuredContent: inv };
      } catch (error) {
        return { content: [{ type: "text", text: `Error: ${error instanceof Error ? error.message : String(error)}` }] };
      }
    }
  );

  // ── wave_create_invoice ───────────────────────────────────────────────────

  server.registerTool(
    "wave_create_invoice",
    {
      title: "Create Wave Invoice",
      description: `Create a new draft invoice in Wave.

Args:
  - businessId (string): Wave business ID
  - customerId (string): Customer ID for the invoice
  - invoiceDate (string): Invoice date in YYYY-MM-DD format (optional, defaults to today)
  - dueDate (string): Due date in YYYY-MM-DD format (optional)
  - invoiceNumber (string): Custom invoice number (optional, auto-assigned if omitted)
  - memo (string): Note to appear on invoice (optional)
  - items (array): Line items (required, at least 1)
    - productId (string): Product ID (optional)
    - description (string): Item description
    - quantity (number): Quantity
    - unitPrice (number): Unit price
    - accountId (string): Revenue account ID (optional)
  - response_format ('markdown' | 'json'): Output format (default: 'markdown')

Returns:
  Created invoice details or validation errors.`,
      inputSchema: z.object({
        businessId: z.string().describe("Wave business ID"),
        customerId: z.string().describe("Customer ID"),
        invoiceDate: z.string().regex(/^\d{4}-\d{2}-\d{2}$/).optional().describe("Invoice date (YYYY-MM-DD)"),
        dueDate: z.string().regex(/^\d{4}-\d{2}-\d{2}$/).optional().describe("Due date (YYYY-MM-DD)"),
        invoiceNumber: z.string().optional().describe("Custom invoice number"),
        memo: z.string().optional().describe("Memo/note on invoice"),
        items: z.array(z.object({
          productId: z.string().optional().describe("Product ID"),
          description: z.string().optional().describe("Line item description"),
          quantity: z.number().min(0.001).describe("Quantity"),
          unitPrice: z.number().describe("Unit price"),
          accountId: z.string().optional().describe("Revenue account ID"),
        })).min(1).describe("Line items (at least 1 required)"),
        response_format: z.enum(["markdown", "json"]).default("markdown").describe("Output format"),
      }),
      annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: false, openWorldHint: true },
    },
    async ({ businessId, customerId, invoiceDate, dueDate, invoiceNumber, memo, items, response_format }) => {
      try {
        const input: Record<string, unknown> = {
          businessId,
          customerId,
          items: items.map((item) => {
            const li: Record<string, unknown> = {
              quantity: item.quantity,
              unitPrice: item.unitPrice,
            };
            if (item.productId) li.productId = item.productId;
            if (item.description) li.description = item.description;
            if (item.accountId) li.accountId = item.accountId;
            return li;
          }),
        };
        if (invoiceDate) input.invoiceDate = invoiceDate;
        if (dueDate) input.dueDate = dueDate;
        if (invoiceNumber) input.invoiceNumber = invoiceNumber;
        if (memo) input.memo = memo;

        const data = await client.query<InvoiceCreateData>(`
          mutation($input: InvoiceCreateInput!) {
            invoiceCreate(input: $input) {
              didSucceed
              inputErrors { code message path }
              invoice { ${INVOICE_FIELDS} }
            }
          }
        `, { input });

        const result = data.invoiceCreate;
        if (!result.didSucceed) {
          const errs = result.inputErrors.map((e) => `  - ${e.path?.join(".") ?? "field"}: ${e.message}`).join("\n");
          return { content: [{ type: "text", text: `Failed to create invoice:\n${errs}` }] };
        }

        let text: string;
        if (response_format === "json") {
          text = JSON.stringify(result.invoice, null, 2);
        } else {
          text = `Invoice created successfully!\n\n${formatInvoiceMarkdown(result.invoice!).join("\n")}`;
        }

        return { content: [{ type: "text", text }], structuredContent: result.invoice };
      } catch (error) {
        return { content: [{ type: "text", text: `Error: ${error instanceof Error ? error.message : String(error)}` }] };
      }
    }
  );

  // ── wave_approve_invoice ──────────────────────────────────────────────────

  server.registerTool(
    "wave_approve_invoice",
    {
      title: "Approve Wave Invoice",
      description: `Approve a draft invoice, moving it to APPROVED status so it can be sent.

Args:
  - invoiceId (string): Invoice ID to approve

Returns:
  Success confirmation or error details.`,
      inputSchema: z.object({
        invoiceId: z.string().describe("Invoice ID to approve"),
      }),
      annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: true, openWorldHint: true },
    },
    async ({ invoiceId }) => {
      try {
        const data = await client.query<InvoiceActionData>(`
          mutation($input: InvoiceApproveInput!) {
            invoiceApprove(input: $input) {
              didSucceed
              inputErrors { message }
            }
          }
        `, { input: { invoiceId } });

        const result = data.invoiceApprove!;
        if (!result.didSucceed) {
          const errs = result.inputErrors.map((e) => `  - ${e.message}`).join("\n");
          return { content: [{ type: "text", text: `Failed to approve invoice:\n${errs}` }] };
        }

        return { content: [{ type: "text", text: `Invoice ${invoiceId} approved successfully.` }] };
      } catch (error) {
        return { content: [{ type: "text", text: `Error: ${error instanceof Error ? error.message : String(error)}` }] };
      }
    }
  );

  // ── wave_send_invoice ─────────────────────────────────────────────────────

  server.registerTool(
    "wave_send_invoice",
    {
      title: "Send Wave Invoice",
      description: `Send an approved invoice to the customer via email.

Args:
  - invoiceId (string): Invoice ID to send
  - to (array of strings): Recipient email addresses
  - subject (string): Email subject (optional)
  - message (string): Email message body (optional)

Returns:
  Success confirmation or error details.`,
      inputSchema: z.object({
        invoiceId: z.string().describe("Invoice ID to send"),
        to: z.array(z.string().email()).min(1).describe("Recipient email addresses"),
        subject: z.string().optional().describe("Email subject line"),
        message: z.string().optional().describe("Email message body"),
      }),
      annotations: { readOnlyHint: false, destructiveHint: false, idempotentHint: false, openWorldHint: true },
    },
    async ({ invoiceId, to, subject, message }) => {
      try {
        const input: Record<string, unknown> = { invoiceId, to };
        if (subject) input.subject = subject;
        if (message) input.message = message;

        const data = await client.query<InvoiceActionData>(`
          mutation($input: InvoiceSendInput!) {
            invoiceSend(input: $input) {
              didSucceed
              inputErrors { message }
            }
          }
        `, { input });

        const result = data.invoiceSend!;
        if (!result.didSucceed) {
          const errs = result.inputErrors.map((e) => `  - ${e.message}`).join("\n");
          return { content: [{ type: "text", text: `Failed to send invoice:\n${errs}` }] };
        }

        return { content: [{ type: "text", text: `Invoice ${invoiceId} sent to ${to.join(", ")}.` }] };
      } catch (error) {
        return { content: [{ type: "text", text: `Error: ${error instanceof Error ? error.message : String(error)}` }] };
      }
    }
  );

  // ── wave_delete_invoice ───────────────────────────────────────────────────

  server.registerTool(
    "wave_delete_invoice",
    {
      title: "Delete Wave Invoice",
      description: `Delete an invoice. Only DRAFT invoices can be deleted; paid invoices cannot be deleted.

⚠️ This action is irreversible.

Args:
  - businessId (string): Wave business ID
  - invoiceId (string): Invoice ID to delete

Returns:
  Success confirmation or error details.`,
      inputSchema: z.object({
        businessId: z.string().describe("Wave business ID"),
        invoiceId: z.string().describe("Invoice ID to delete"),
      }),
      annotations: { readOnlyHint: false, destructiveHint: true, idempotentHint: false, openWorldHint: true },
    },
    async ({ businessId, invoiceId }) => {
      try {
        const data = await client.query<InvoiceActionData>(`
          mutation($input: InvoiceDeleteInput!) {
            invoiceDelete(input: $input) {
              didSucceed
              inputErrors { message }
            }
          }
        `, { input: { businessId, invoiceId } });

        const result = data.invoiceDelete!;
        if (!result.didSucceed) {
          const errs = result.inputErrors.map((e) => `  - ${e.message}`).join("\n");
          return { content: [{ type: "text", text: `Failed to delete invoice:\n${errs}` }] };
        }

        return { content: [{ type: "text", text: `Invoice ${invoiceId} deleted successfully.` }] };
      } catch (error) {
        return { content: [{ type: "text", text: `Error: ${error instanceof Error ? error.message : String(error)}` }] };
      }
    }
  );
}