import { useMemo, useState } from "react";
import { Alert, Box, CircularProgress, Stack, Tab, Tabs, Typography } from "@mui/material";
import type { GridRowParams, GridRowSelectionModel } from "@mui/x-data-grid";
import { ColumnsDrawer } from "@/dashboard/ColumnsDrawer";
import { InvoiceFilterToolbar } from "@/dashboard/InvoiceFilterToolbar";
import { CreatePayRunButton } from "@/dashboard/CreatePayRunButton";
import { InvoiceDataGrid } from "@/dashboard/InvoiceDataGrid";
import { columnsForApprovedGrid, columnsFromCatalogKeys } from "@/dashboard/columns";
import {
  loadColumnPrefs,
  resetColumnPrefs,
  saveColumnPrefs,
  type ColumnPrefs,
} from "@/dashboard/column-prefs";
import { EMPTY_INVOICE_FILTERS, type InvoiceFilterState } from "@/dashboard/invoice-filters";
import { InvoiceTabLabel } from "@/dashboard/invoice-tabs";
import { countSelectedRows } from "@/dashboard/selection";
import { useInvoices, useUpdateInvoicePayDate } from "@/domain/invoices/use-invoices";
import { areMocksEnabled, type MockInvoice } from "@/mocks";
import { useNavigate } from "@/router";

type InvoiceTab = "attention" | "all" | "approved" | "rejected" | "late";

const emptySelection: GridRowSelectionModel = {
  type: "include",
  ids: new Set(),
};

const emptyFilters = EMPTY_INVOICE_FILTERS;

const rowClickSx = {
  border: 1,
  borderColor: "divider",
  backgroundColor: "background.paper",
  cursor: "pointer",
  borderRadius: 1,
} as const;

const invoiceTabsSx = {
  minHeight: 44,
  "& .MuiTab-root": {
    bgcolor: "rgba(47,128,237,0.12)",
    mr: 0.5,
    borderTopLeftRadius: 6,
    borderTopRightRadius: 6,
    color: "text.primary",
    textTransform: "none",
  },
  "& .Mui-selected": {
    bgcolor: "#fff !important",
    color: "text.primary !important",
  },
  "& .MuiTabs-indicator": {
    height: 3,
    borderRadius: 1,
    backgroundColor: "#7B61FF",
  },
} as const;

function applyInvoiceFilters(rows: MockInvoice[], filters: InvoiceFilterState): MockInvoice[] {
  const vendorQuery = filters.vendorQuery.trim().toLowerCase();
  return rows.filter((invoice) => {
    if (filters.action && invoice.actionLabel !== filters.action) {
      return false;
    }
    if (vendorQuery && !invoice.vendorName.toLowerCase().includes(vendorQuery)) {
      return false;
    }
    return true;
  });
}

export function DashboardGrids() {
  const navigate = useNavigate();
  const [tab, setTab] = useState<InvoiceTab>("attention");
  const [selection, setSelection] = useState<GridRowSelectionModel>(emptySelection);
  const [filters, setFilters] = useState<InvoiceFilterState>(emptyFilters);
  const [columnsDrawerOpen, setColumnsDrawerOpen] = useState(false);
  const [, setFilterDrawerOpen] = useState(false);
  const [columnPrefs, setColumnPrefs] = useState<ColumnPrefs>(() => loadColumnPrefs());
  const { data: invoices = [], isLoading, isError, error } = useInvoices();
  const updatePayDate = useUpdateInvoicePayDate();

  const catalogColumns = useMemo(
    () => columnsFromCatalogKeys(columnPrefs.visibleOrder),
    [columnPrefs.visibleOrder],
  );
  const approvedColumns = useMemo(
    () => columnsForApprovedGrid(columnPrefs.visibleOrder),
    [columnPrefs.visibleOrder],
  );

  const openInvoice = (params: GridRowParams<MockInvoice>) => {
    navigate("/invoices/:id", { params: { id: params.row.id } });
  };

  const attentionRows = useMemo(
    () => invoices.filter((invoice) => invoice.status === "pending_approval"),
    [invoices],
  );
  const approvedRows = useMemo(
    () => invoices.filter((invoice) => invoice.status === "approved"),
    [invoices],
  );
  const rejectedRows = useMemo(
    () => invoices.filter((invoice) => invoice.status === "rejected"),
    [invoices],
  );
  const lateRows = useMemo(() => {
    const today = new Date().toISOString().slice(0, 10);
    return invoices.filter(
      (invoice) =>
        invoice.dueDate < today && invoice.status !== "paid" && invoice.status !== "rejected",
    );
  }, [invoices]);

  const filteredAttention = useMemo(
    () => applyInvoiceFilters(attentionRows, filters),
    [attentionRows, filters],
  );
  const filteredAll = useMemo(() => applyInvoiceFilters(invoices, filters), [invoices, filters]);
  const filteredApproved = useMemo(
    () => applyInvoiceFilters(approvedRows, filters),
    [approvedRows, filters],
  );
  const filteredRejected = useMemo(
    () => applyInvoiceFilters(rejectedRows, filters),
    [rejectedRows, filters],
  );
  const filteredLate = useMemo(() => applyInvoiceFilters(lateRows, filters), [lateRows, filters]);

  const selectedCount = countSelectedRows(
    selection,
    approvedRows.map((invoice) => invoice.id),
  );

  const processRowUpdate = async (newRow: MockInvoice, oldRow: MockInvoice) => {
    if (newRow.payDate === oldRow.payDate) {
      return oldRow;
    }
    const nextPayDate = newRow.payDate?.trim() ? newRow.payDate.trim() : null;
    return updatePayDate.mutateAsync({ id: newRow.id, payDate: nextPayDate });
  };

  const updateColumnPrefs = (next: ColumnPrefs) => {
    setColumnPrefs(next);
    saveColumnPrefs(next);
  };

  if (isLoading) {
    return (
      <Box sx={{ display: "flex", justifyContent: "center", py: 6 }}>
        <CircularProgress aria-label="Loading invoices" />
      </Box>
    );
  }

  if (isError) {
    return (
      <Alert severity="error">
        {error instanceof Error ? error.message : "Failed to load invoices"}
      </Alert>
    );
  }

  return (
    <Stack spacing={0} data-testid="invoice-processing">
      <Box sx={{ bgcolor: "#E8EEF7", px: 1, pt: 1 }}>
        <Tabs
          value={tab}
          onChange={(_event, value: InvoiceTab) => {
            setTab(value);
            setSelection(emptySelection);
          }}
          variant="scrollable"
          aria-label="Invoice Processing tabs"
          sx={invoiceTabsSx}
        >
          <Tab
            label={
              <InvoiceTabLabel
                title="For My Attention"
                count={filteredAttention.length}
                active={tab === "attention"}
              />
            }
            value="attention"
            data-testid="tab-pending"
          />
          <Tab
            label={
              <InvoiceTabLabel
                title="New Invoices"
                count={filteredAll.length}
                active={tab === "all"}
              />
            }
            value="all"
            data-testid="tab-all"
          />
          <Tab
            label={
              <InvoiceTabLabel
                title="Approved Invoices"
                count={filteredApproved.length}
                active={tab === "approved"}
              />
            }
            value="approved"
            data-testid="tab-ready"
          />
          <Tab
            label={
              <InvoiceTabLabel
                title="Rejected Invoices"
                count={filteredRejected.length}
                active={tab === "rejected"}
              />
            }
            value="rejected"
            data-testid="tab-rejected"
          />
          <Tab
            label={
              <InvoiceTabLabel
                title="Late Invoices"
                count={filteredLate.length}
                active={tab === "late"}
                urgency
              />
            }
            value="late"
            data-testid="tab-late"
          />
        </Tabs>
      </Box>

      <Box sx={{ bgcolor: "background.paper", p: 2 }}>
        {filteredAttention.length > 0 && tab === "attention" ? (
          <Typography
            data-testid="attention-banner"
            variant="body2"
            sx={{ display: "block", mb: 1.5, color: "primary.main", textAlign: "left" }}
          >
            {filteredAttention.length} invoices require approval.{" "}
            <Box component="span" sx={{ textDecoration: "underline" }}>
              Show invoices ready to approve.
            </Box>
          </Typography>
        ) : null}

        <InvoiceFilterToolbar
          filters={filters}
          onFiltersChange={setFilters}
          onOpenFilterDrawer={() => setFilterDrawerOpen(true)}
          onOpenColumnsDrawer={() => setColumnsDrawerOpen(true)}
          trailingActions={
            tab === "approved" ? <CreatePayRunButton selectedCount={selectedCount} /> : null
          }
        />

        {tab === "attention" && (
          <InvoiceDataGrid
            data-testid="grid-pending"
            rows={filteredAttention}
            columns={catalogColumns}
            onRowClick={openInvoice}
            sx={rowClickSx}
          />
        )}

        {tab === "all" && (
          <InvoiceDataGrid
            data-testid="grid-all"
            rows={filteredAll}
            columns={catalogColumns}
            onRowClick={openInvoice}
            sx={rowClickSx}
          />
        )}

        {tab === "approved" && (
          <InvoiceDataGrid
            data-testid="grid-ready"
            rows={filteredApproved}
            columns={approvedColumns}
            checkboxSelection
            rowSelectionModel={selection}
            onRowSelectionModelChange={(model) => setSelection(model)}
            processRowUpdate={processRowUpdate}
            onProcessRowUpdateError={(processError) => {
              console.error(processError);
            }}
            sx={rowClickSx}
          />
        )}

        {tab === "rejected" && (
          <InvoiceDataGrid
            data-testid="grid-rejected"
            rows={filteredRejected}
            columns={catalogColumns}
            onRowClick={openInvoice}
            sx={rowClickSx}
          />
        )}

        {tab === "late" && (
          <InvoiceDataGrid
            data-testid="grid-late"
            rows={filteredLate}
            columns={catalogColumns}
            onRowClick={openInvoice}
            sx={rowClickSx}
          />
        )}

        <Typography variant="body2" data-testid="mocks-status" sx={{ mt: 2 }}>
          Mocks {areMocksEnabled() ? "enabled" : "disabled"} — {invoices.length} invoices
        </Typography>
      </Box>

      <ColumnsDrawer
        open={columnsDrawerOpen}
        onClose={() => setColumnsDrawerOpen(false)}
        prefs={columnPrefs}
        onPrefsChange={updateColumnPrefs}
        onReset={() => {
          const next = resetColumnPrefs();
          setColumnPrefs(next);
        }}
      />
    </Stack>
  );
}