import { Mark, mergeAttributes } from '@tiptap/core'

import type { TextStyleAttributes } from '../index.js'

export interface TextStyleOptions {
  /**
   * HTML attributes to add to the span element.
   * @default {}
   * @example { class: 'foo' }
   */
  HTMLAttributes: Record<string, any>
  /**
   * When enabled, merges the styles of nested spans into the child span during HTML parsing.
   * This prioritizes the style of the child span.
   * Used when parsing content created in other editors.
   * (Fix for ProseMirror's default behavior.)
   * @default true
   */
  mergeNestedSpanStyles: boolean
}

declare module '@tiptap/core' {
  interface Commands<ReturnType> {
    textStyle: {
      /**
       * Remove spans without inline style attributes.
       * @example editor.commands.removeEmptyTextStyle()
       */
      removeEmptyTextStyle: () => ReturnType
      /**
       * Toggle a text style
       * @param attributes The text style attributes
       * @example editor.commands.toggleTextStyle({ fontWeight: 'bold' })
       */
      toggleTextStyle: (attributes?: TextStyleAttributes) => ReturnType
    }
  }
}

const MAX_FIND_CHILD_SPAN_DEPTH = 20

/**
 * Returns all next child spans, either direct children or nested deeper
 * but won't traverse deeper into child spans found, will only go MAX_FIND_CHILD_SPAN_DEPTH levels deep (default: 20)
 */
const findChildSpans = (element: HTMLElement, depth = 0): HTMLElement[] => {
  const childSpans: HTMLElement[] = []

  if (!element.children.length || depth > MAX_FIND_CHILD_SPAN_DEPTH) {
    return childSpans
  }

  Array.from(element.children).forEach(child => {
    if (child.tagName === 'SPAN') {
      childSpans.push(child as HTMLElement)
    } else if (child.children.length) {
      childSpans.push(...findChildSpans(child as HTMLElement, depth + 1))
    }
  })

  return childSpans
}

const mergeNestedSpanStyles = (element: HTMLElement) => {
  if (!element.children.length) {
    return
  }

  const childSpans = findChildSpans(element)

  if (!childSpans) {
    return
  }

  childSpans.forEach(childSpan => {
    const childStyle = childSpan.getAttribute('style')
    const closestParentSpanStyleOfChild = childSpan.parentElement?.closest('span')?.getAttribute('style')

    childSpan.setAttribute('style', `${closestParentSpanStyleOfChild};${childStyle}`)
  })
}

/**
 * This extension allows you to create text styles. It is required by default
 * for the `text-color` and `font-family` extensions.
 * @see https://www.tiptap.dev/api/marks/text-style
 */
export const TextStyle = Mark.create<TextStyleOptions>({
  name: 'textStyle',

  priority: 101,

  addOptions() {
    return {
      HTMLAttributes: {},
      mergeNestedSpanStyles: true,
    }
  },

  parseHTML() {
    return [
      {
        tag: 'span',
        consuming: false,
        getAttrs: element => {
          const hasStyles = (element as HTMLElement).hasAttribute('style')

          if (!hasStyles) {
            return false
          }

          if (this.options.mergeNestedSpanStyles) {
            mergeNestedSpanStyles(element)
          }

          return {}
        },
      },
    ]
  },

  renderHTML({ HTMLAttributes }) {
    return ['span', mergeAttributes(this.options.HTMLAttributes, HTMLAttributes), 0]
  },

  addCommands() {
    return {
      toggleTextStyle:
        attributes =>
        ({ commands }) => {
          return commands.toggleMark(this.name, attributes)
        },
      removeEmptyTextStyle:
        () =>
        ({ tr }) => {
          const { selection } = tr

          // Gather all of the nodes within the selection range.
          // We would need to go through each node individually
          // to check if it has any inline style attributes.
          // Otherwise, calling commands.unsetMark(this.name)
          // removes everything from all the nodes
          // within the selection range.
          tr.doc.nodesBetween(selection.from, selection.to, (node, pos) => {
            // Check if it's a paragraph element, if so, skip this node as we apply
            // the text style to inline text nodes only (span).
            if (node.isTextblock) {
              return true
            }

            // Check if the node has no inline style attributes.
            // Filter out non-`textStyle` marks.
            if (
              !node.marks
                .filter(mark => mark.type === this.type)
                .some(mark => Object.values(mark.attrs).some(value => !!value))
            ) {
              // Proceed with the removal of the `textStyle` mark for this node only
              tr.removeMark(pos, pos + node.nodeSize, this.type)
            }
          })

          return true
        },
    }
  },
})