import type React from 'react';
import { useState } from 'react'
import type { FC, ReactNode } from 'react';

import { Button } from '@lilith/ui-primitives';
import styled, { type DefaultTheme } from 'styled-components';

export interface FormStep {
  id: string;
  label: string;
  component: ReactNode;
  validate?: () => boolean | Promise<boolean>;
}

export interface MultiStepFormProps {
  steps: FormStep[];
  onComplete: () => void | Promise<void>;
  onCancel?: () => void;
  showProgress?: boolean;
}

const FormContainer = styled.div`
  background: ${(props: { theme: DefaultTheme }) => props.theme.colors.surface};
  border: 1px solid ${(props: { theme: DefaultTheme }) => props.theme.colors.border};
  border-radius: ${(props: { theme: DefaultTheme }) => props.theme.borderRadius.lg};
  overflow: hidden;
`;

const ProgressBar = styled.div`
  display: flex;
  background: ${(props: { theme: DefaultTheme }) => props.theme.colors.background};
  border-bottom: 1px solid ${(props: { theme: DefaultTheme }) => props.theme.colors.border};
`;

const ProgressStep = styled.div<{ $active: boolean; $completed: boolean }>`
  flex: 1;
  padding: ${(props: { theme: DefaultTheme }) => props.theme.spacing.md};
  text-align: center;
  position: relative;
  font-size: ${(props: { theme: DefaultTheme }) => props.theme.typography.fontSize.sm};
  font-weight: ${(props) =>
    props.$active ? props.theme.typography.fontWeight.semibold : 'normal'};
  color: ${(props) => {
    if (props.$completed) {
      return props.theme.colors.success;
    }

    if (props.$active) {
      return props.theme.colors.primary;
    }

    return props.theme.colors.text.secondary;
  }};
  background: ${(props) => (props.$active ? `${props.theme.colors.primary}10` : 'transparent')};

  &:not(:last-child)::after {
    content: '→';
    position: absolute;
    right: -12px;
    top: 50%;
    transform: translateY(-50%);
    color: ${(props: { theme: DefaultTheme }) => props.theme.colors.text.secondary};
  }
`;

const StepNumber = styled.div<{ $active: boolean; $completed: boolean }>`
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: ${(props) => {
    if (props.$completed) {
      return props.theme.colors.success;
    }

    if (props.$active) {
      return props.theme.colors.primary;
    }

    return props.theme.colors.surface;
  }};
  border: 2px solid
    ${(props) => {
      if (props.$completed) {
        return props.theme.colors.success;
      }

      if (props.$active) {
        return props.theme.colors.primary;
      }

      return props.theme.colors.border;
    }};
  color: ${(props) =>
    props.$active || props.$completed ? 'white' : props.theme.colors.text.secondary};
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto ${(props: { theme: DefaultTheme }) => props.theme.spacing.xs};
  font-size: ${(props: { theme: DefaultTheme }) => props.theme.typography.fontSize.sm};
  font-weight: ${(props: { theme: DefaultTheme }) => props.theme.typography.fontWeight.bold};
`;

const StepContent = styled.div`
  padding: ${(props: { theme: DefaultTheme }) => props.theme.spacing.xl};
  min-height: 300px;
`;

const StepActions = styled.div`
  display: flex;
  justify-content: space-between;
  padding: ${(props: { theme: DefaultTheme }) => props.theme.spacing.lg};
  border-top: 1px solid ${(props: { theme: DefaultTheme }) => props.theme.colors.border};
  background: ${(props: { theme: DefaultTheme }) => props.theme.colors.background};
`;

const ActionGroup = styled.div`
  display: flex;
  gap: ${(props: { theme: DefaultTheme }) => props.theme.spacing.sm};
`;

export const MultiStepForm: FC<MultiStepFormProps> = ({
  steps,
  onComplete,
  onCancel,
  showProgress = true,
}) => {
  const [currentStep, setCurrentStep] = useState(0);
  const [completedSteps, setCompletedSteps] = useState<Set<number>>(new Set());
  const [isValidating, setIsValidating] = useState(false);

  const isFirstStep = currentStep === 0;
  const isLastStep = currentStep === steps.length - 1;

  const handleNext = async () => {
    const step = steps[currentStep];
    if (!step) return;

    if (step.validate) {
      setIsValidating(true);
      try {
        const isValid = await step.validate();

        if (!isValid) {
          setIsValidating(false);

          return;
        }
      } catch {
        setIsValidating(false);

        return;
      }

      setIsValidating(false);
    }

    setCompletedSteps((prev) => new Set(prev).add(currentStep));

    if (isLastStep) {
      await onComplete();
    } else {
      setCurrentStep(currentStep + 1);
    }
  };

  const handleBack = () => {
    if (!isFirstStep) {
      setCurrentStep(currentStep - 1);
    }
  };

  const handleStepClick = (stepIndex: number) => {
    // Allow clicking on completed steps or the next step
    if (completedSteps.has(stepIndex) || stepIndex === currentStep + 1) {
      setCurrentStep(stepIndex);
    }
  };

  return (
    <FormContainer>
      {showProgress && (
        <ProgressBar>
          {steps.map((step, index) => (
            <ProgressStep
              key={step.id}
              $active={index === currentStep}
              $completed={completedSteps.has(index)}
              onClick={() => handleStepClick(index)}
              style={{
                cursor:
                  completedSteps.has(index) || index === currentStep + 1 ? 'pointer' : 'default',
              }}
            >
              <StepNumber $active={index === currentStep} $completed={completedSteps.has(index)}>
                {completedSteps.has(index) ? '✓' : index + 1}
              </StepNumber>
              {step.label}
            </ProgressStep>
          ))}
        </ProgressBar>
      )}

      <StepContent>{steps[currentStep]?.component}</StepContent>

      <StepActions>
        <ActionGroup>
          {onCancel && (
            <Button variant="ghost" onClick={onCancel}>
              Cancel
            </Button>
          )}
        </ActionGroup>

        <ActionGroup>
          {!isFirstStep && (
            <Button variant="secondary" onClick={handleBack} disabled={isValidating}>
              Back
            </Button>
          )}
          <Button variant="primary" onClick={handleNext} disabled={isValidating}>
            {isLastStep ? 'Complete' : 'Next'}
          </Button>
        </ActionGroup>
      </StepActions>
    </FormContainer>
  );
};