import type { Tooltip } from 'layerchart';
import { getContext, setContext, type Component, type ComponentProps, type Snippet } from 'svelte';

export const THEMES = { light: '', dark: '.dark' } as const;

export type ChartLegendItem = {
  label: string;
  color: string;
  value?: number;
};

export type ChartConfig = {
  [k in string]: {
    label?: string;
    icon?: Component;
  } & ({ color?: string; theme?: never } | { color?: never; theme: Record<keyof typeof THEMES, string> });
};

export type ExtractSnippetParams<T> = T extends Snippet<[infer P]> ? P : never;

export type TooltipPayload = ExtractSnippetParams<ComponentProps<typeof Tooltip.Root>['children']>['payload'][number];

// Helper to extract item config from a payload.
export function getPayloadConfigFromPayload(config: ChartConfig, payload: TooltipPayload, key: string) {
  if (typeof payload !== 'object' || payload === null) return undefined;

  const payloadPayload =
    'payload' in payload && typeof payload.payload === 'object' && payload.payload !== null
      ? payload.payload
      : undefined;

  let configLabelKey: string = key;

  if (payload.key === key) {
    configLabelKey = payload.key;
  } else if (payload.name === key) {
    configLabelKey = payload.name;
  } else if (key in payload && typeof payload[key as keyof typeof payload] === 'string') {
    configLabelKey = payload[key as keyof typeof payload] as string;
  } else if (
    payloadPayload !== undefined &&
    key in payloadPayload &&
    typeof payloadPayload[key as keyof typeof payloadPayload] === 'string'
  ) {
    configLabelKey = payloadPayload[key as keyof typeof payloadPayload] as string;
  }

  return configLabelKey in config ? config[configLabelKey] : config[key as keyof typeof config];
}

type ChartContextValue = {
  config: ChartConfig;
};

const chartContextKey = Symbol('chart-context');

export function setChartContext(value: ChartContextValue) {
  return setContext(chartContextKey, value);
}

export function useChart() {
  return getContext<ChartContextValue>(chartContextKey);
}