import {
  Alert,
  Box,
  Button,
  CircularProgress,
  MenuItem,
  Snackbar,
  Stack,
  TextField,
  Typography,
} from "@mui/material";
import { useState, type ReactNode } from "react";

export type SettingsFormField =
  | {
      name: string;
      label: string;
      type?: "text" | "email" | "number";
      required?: boolean;
    }
  | {
      name: string;
      label: string;
      type: "select";
      required?: boolean;
      options: Array<{ value: string; label: string }>;
    };

type SettingsFormShellProps = {
  title: string;
  testId: string;
  fields: SettingsFormField[];
  initialValues: Record<string, string>;
  formKey?: string;
  isLoading?: boolean;
  isError?: boolean;
  errorMessage?: string;
  notFound?: boolean;
  onCancel: () => void;
  onSave: (values: Record<string, string>) => Promise<void>;
  extra?: ReactNode;
};

type SettingsFormFieldsProps = {
  title: string;
  testId: string;
  fields: SettingsFormField[];
  initialValues: Record<string, string>;
  onCancel: () => void;
  onSave: (values: Record<string, string>) => Promise<void>;
  extra?: ReactNode;
};

function SettingsFormFields({
  title,
  testId,
  fields,
  initialValues,
  onCancel,
  onSave,
  extra,
}: SettingsFormFieldsProps) {
  const [values, setValues] = useState(initialValues);
  const [saving, setSaving] = useState(false);
  const [snackbar, setSnackbar] = useState<string | null>(null);
  const [validationError, setValidationError] = useState<string | null>(null);

  const handleSave = async () => {
    for (const field of fields) {
      if (field.required !== false && !values[field.name]?.trim()) {
        setValidationError(`${field.label} is required.`);
        return;
      }
    }

    setValidationError(null);
    setSaving(true);
    try {
      await onSave(values);
      setSnackbar("Saved to mock store");
    } catch (error) {
      setValidationError(error instanceof Error ? error.message : "Save failed");
    } finally {
      setSaving(false);
    }
  };

  return (
    <Stack spacing={3} data-testid={testId}>
      <Typography component="h1" variant="h1">
        {title}
      </Typography>

      {validationError ? <Alert severity="error">{validationError}</Alert> : null}

      <Stack
        spacing={2}
        sx={{
          maxWidth: 480,
        }}
      >
        {fields.map((field) => {
          if (field.type === "select") {
            return (
              <TextField
                key={field.name}
                select
                label={field.label}
                value={values[field.name] ?? ""}
                onChange={(event) =>
                  setValues((current) => ({ ...current, [field.name]: event.target.value }))
                }
                required={field.required !== false}
                data-testid={`${testId}-field-${field.name}`}
              >
                {field.options.map((option) => (
                  <MenuItem key={option.value} value={option.value}>
                    {option.label}
                  </MenuItem>
                ))}
              </TextField>
            );
          }

          return (
            <TextField
              key={field.name}
              label={field.label}
              type={field.type ?? "text"}
              value={values[field.name] ?? ""}
              onChange={(event) =>
                setValues((current) => ({ ...current, [field.name]: event.target.value }))
              }
              required={field.required !== false}
              data-testid={`${testId}-field-${field.name}`}
            />
          );
        })}
        {extra}
      </Stack>

      <Stack direction="row" spacing={1}>
        <Button variant="contained" onClick={() => void handleSave()} disabled={saving}>
          Save
        </Button>
        <Button variant="outlined" onClick={onCancel} disabled={saving}>
          Cancel
        </Button>
      </Stack>

      <Snackbar
        open={Boolean(snackbar)}
        autoHideDuration={2500}
        onClose={() => setSnackbar(null)}
        message={snackbar}
        data-testid={`${testId}-snackbar`}
      />
    </Stack>
  );
}

export function SettingsFormShell({
  title,
  testId,
  fields,
  initialValues,
  formKey = "new",
  isLoading = false,
  isError = false,
  errorMessage,
  notFound = false,
  onCancel,
  onSave,
  extra,
}: SettingsFormShellProps) {
  if (isLoading) {
    return (
      <Box sx={{ display: "flex", justifyContent: "center", py: 6 }}>
        <CircularProgress aria-label={`Loading ${title}`} />
      </Box>
    );
  }

  if (isError) {
    return (
      <Alert severity="error">{errorMessage ?? `Failed to load ${title.toLowerCase()}`}</Alert>
    );
  }

  if (notFound) {
    return <Alert severity="warning">Record not found.</Alert>;
  }

  return (
    <SettingsFormFields
      key={formKey}
      title={title}
      testId={testId}
      fields={fields}
      initialValues={initialValues}
      onCancel={onCancel}
      onSave={onSave}
      extra={extra}
    />
  );
}