import { Annotation, type ChangeSpec, type Transaction } from '@codemirror/state'

export type CoreInlineSpecName = 'bold' | 'italic' | 'strike' | 'inline-code'
export type InlineSemanticSpecName = CoreInlineSpecName | (string & {})

export type InlineSemanticMarkOp =
  | {
      readonly kind: 'add-mark'
      readonly specName: InlineSemanticSpecName
      readonly range: { readonly start: number; readonly end: number }
      readonly attrs: unknown
    }
  | {
      readonly kind: 'unmark'
      readonly specName: InlineSemanticSpecName
      readonly range: { readonly start: number; readonly end: number }
    }
  | {
      readonly kind: 'synthesize-paste'
      readonly range: { readonly start: number; readonly end: number }
    }

export interface InlineSemanticChange {
  readonly ops: ReadonlyArray<InlineSemanticMarkOp>
}

export interface InlineSemanticTextChange {
  readonly from: number
  readonly to: number
  readonly insert: string
}

const CORE_INLINE_SPEC_NAMES = {
  '**': 'bold',
  '__': 'bold',
  '*': 'italic',
  '_': 'italic',
  '~~': 'strike',
  '`': 'inline-code',
  '``': 'inline-code',
  '```': 'inline-code',
} as const satisfies Record<string, CoreInlineSpecName>

export function coreInlineSpecNameForDelimiter(delimiter: string): CoreInlineSpecName | undefined {
  return CORE_INLINE_SPEC_NAMES[delimiter as keyof typeof CORE_INLINE_SPEC_NAMES]
}

export const INLINE_SEMANTIC_CHANGE_ANNOTATION = Annotation.define<InlineSemanticChange>()
export const INLINE_SEMANTIC_TEXT_CHANGE_ANNOTATION = Annotation.define<InlineSemanticTextChange>()

export function readInlineSemanticChange(
  transaction: Transaction,
): InlineSemanticChange | undefined {
  return transaction.annotation(INLINE_SEMANTIC_CHANGE_ANNOTATION)
}

export function inlineSemanticTextChangeFromChangeSpec(
  change: ChangeSpec,
): InlineSemanticTextChange | undefined {
  if (
    typeof change === 'object'
    && change !== null
    && !Array.isArray(change)
    && 'from' in change
    && 'to' in change
    && 'insert' in change
    && typeof (change as { insert: unknown }).insert === 'string'
  ) {
    return {
      from: (change as { from: number }).from,
      to: (change as { to: number }).to,
      insert: (change as { insert: string }).insert,
    }
  }
  return undefined
}

export function readInlineSemanticTextChange(
  transaction: Transaction,
): InlineSemanticTextChange | undefined {
  return transaction.annotation(INLINE_SEMANTIC_TEXT_CHANGE_ANNOTATION)
}