toon/src/encoders.ts

import type {
  Depth,
  JsonArray,
  JsonObject,
  JsonPrimitive,
  JsonValue,
  ResolvedEncodeOptions,
} from './types'
import { LIST_ITEM_MARKER, LIST_ITEM_PREFIX } from './constants'
import {
  isArrayOfArrays,
  isArrayOfObjects,
  isArrayOfPrimitives,
  isJsonArray,
  isJsonObject,
  isJsonPrimitive,
} from './normalize'
import {
  encodeKey,
  encodePrimitive,
  formatArrayHeader,
  formatKeyedArrayHeader,
  formatKeyedTableHeader,
  formatTabularHeader,
  joinEncodedValues,
} from './primitives'
import { LineWriter } from './writer'

// #region Encode normalized JsonValue

export function encodeValue(value: JsonValue, options: ResolvedEncodeOptions): string {
  if (isJsonPrimitive(value)) {
    return encodePrimitive(value)
  }

  const writer = new LineWriter(options.indent)

  if (isJsonArray(value)) {
    encodeRootArray(value, writer)
  }
  else if (isJsonObject(value)) {
    encodeObject(value, writer, 0)
  }

  return writer.toString()
}

// #endregion

// #region Object encoding

export function encodeObject(value: JsonObject, writer: LineWriter, depth: Depth): void {
  const keys = Object.keys(value)

  for (const key of keys) {
    encodeKeyValuePair(key, value[key]!, writer, depth)
  }
}

export function encodeKeyValuePair(key: string, value: JsonValue, writer: LineWriter, depth: Depth): void {
  const encodedKey = encodeKey(key)

  if (isJsonPrimitive(value)) {
    writer.push(depth, `${encodedKey}: ${encodePrimitive(value)}`)
  }
  else if (isJsonArray(value)) {
    encodeArrayProperty(key, value, writer, depth)
  }
  else if (isJsonObject(value)) {
    const nestedKeys = Object.keys(value)
    if (nestedKeys.length === 0) {
      // Empty object
      writer.push(depth, `${encodedKey}:`)
    }
    else {
      writer.push(depth, `${encodedKey}:`)
      encodeObject(value, writer, depth + 1)
    }
  }
}

// #endregion

// #region Array encoding

export function encodeRootArray(value: JsonArray, writer: LineWriter): void {
  if (value.length === 0) {
    writer.push(0, '[0]:')
    return
  }

  // Primitive array
  if (isArrayOfPrimitives(value)) {
    encodeInlinePrimitiveArray(undefined, value, writer, 0)
    return
  }

  // Array of arrays (all primitives)
  if (isArrayOfArrays(value)) {
    const allPrimitiveArrays = value.every(arr => isArrayOfPrimitives(arr))
    if (allPrimitiveArrays) {
      encodeArrayOfArraysAsListItems(undefined, value, writer, 0)
      return
    }
  }

  // Array of objects
  if (isArrayOfObjects(value)) {
    const header = detectTabularHeader(value)
    if (header) {
      encodeArrayOfObjectsAsTabular(undefined, value, header, writer, 0)
    }
    else {
      encodeArrayOfObjectsAsListItems(undefined, value, writer, 0)
    }
    return
  }

  // Mixed array: fallback to expanded format (not in spec, but safe default)
  encodeMixedArrayAsListItems(undefined, value, writer, 0)
}

export function encodeArrayProperty(key: string, value: JsonArray, writer: LineWriter, depth: Depth): void {
  if (value.length === 0) {
    const encodedKey = encodeKey(key)
    writer.push(depth, `${encodedKey}[0]:`)
    return
  }

  // Primitive array
  if (isArrayOfPrimitives(value)) {
    encodeInlinePrimitiveArray(key, value, writer, depth)
    return
  }

  // Array of arrays (all primitives)
  if (isArrayOfArrays(value)) {
    const allPrimitiveArrays = value.every(arr => isArrayOfPrimitives(arr))
    if (allPrimitiveArrays) {
      encodeArrayOfArraysAsListItems(key, value, writer, depth)
      return
    }
  }

  // Array of objects
  if (isArrayOfObjects(value)) {
    const header = detectTabularHeader(value)
    if (header) {
      encodeArrayOfObjectsAsTabular(key, value, header, writer, depth)
    }
    else {
      encodeArrayOfObjectsAsListItems(key, value, writer, depth)
    }
    return
  }

  // Mixed array: fallback to expanded format
  encodeMixedArrayAsListItems(key, value, writer, depth)
}

// #endregion

// #region Primitive array encoding (inline)

export function encodeInlinePrimitiveArray(
  prefix: string | undefined,
  values: readonly JsonPrimitive[],
  writer: LineWriter,
  depth: Depth,
): void {
  const header = prefix ? formatKeyedArrayHeader(prefix, values.length) : formatArrayHeader(values.length)
  const joinedValue = joinEncodedValues(values)
  // Only add space if there are values
  if (values.length === 0) {
    writer.push(depth, header)
  }
  else {
    writer.push(depth, `${header} ${joinedValue}`)
  }
}

// #endregion

// #region Array of arrays (expanded format)

export function encodeArrayOfArraysAsListItems(
  prefix: string | undefined,
  values: readonly JsonArray[],
  writer: LineWriter,
  depth: Depth,
): void {
  const header = prefix ? formatKeyedArrayHeader(prefix, values.length) : formatArrayHeader(values.length)
  writer.push(depth, header)

  for (const arr of values) {
    if (isArrayOfPrimitives(arr)) {
      const inline = formatInlineArray(arr)
      writer.push(depth + 1, `${LIST_ITEM_PREFIX}${inline}`)
    }
  }
}

export function formatInlineArray(values: readonly JsonPrimitive[]): string {
  const header = formatArrayHeader(values.length)
  const joinedValue = joinEncodedValues(values)
  // Only add space if there are values
  if (values.length === 0) {
    return header
  }
  return `${header} ${joinedValue}`
}

// #endregion

// #region Array of objects (tabular format)

export function encodeArrayOfObjectsAsTabular(
  prefix: string | undefined,
  rows: readonly JsonObject[],
  header: readonly string[],
  writer: LineWriter,
  depth: Depth,
): void {
  const headerStr = prefix
    ? formatKeyedTableHeader(prefix, rows.length, header)
    : formatTabularHeader(rows.length, header)
  writer.push(depth, `${headerStr}`)

  for (const row of rows) {
    const values = header.map(key => row[key])
    const joinedValue = joinEncodedValues(values as JsonPrimitive[])
    writer.push(depth + 1, joinedValue)
  }
}

export function detectTabularHeader(rows: readonly JsonObject[]): string[] | undefined {
  if (rows.length === 0)
    return

  const firstRow = rows[0]!
  const firstKeys = Object.keys(firstRow)
  if (firstKeys.length === 0)
    return

  if (isTabularArray(rows, firstKeys)) {
    return firstKeys
  }
}

export function isTabularArray(
  rows: readonly JsonObject[],
  header: readonly string[],
): boolean {
  for (const row of rows) {
    const keys = Object.keys(row)

    // All objects must have the same keys (but order can differ)
    if (keys.length !== header.length) {
      return false
    }

    // Check that all header keys exist in the row and all values are primitives
    for (const key of header) {
      if (!(key in row)) {
        return false
      }
      if (!isJsonPrimitive(row[key])) {
        return false
      }
    }
  }

  return true
}

// #endregion

// #region Array of objects (expanded format)

export function encodeMixedArrayAsListItems(
  prefix: string | undefined,
  items: readonly JsonValue[],
  writer: LineWriter,
  depth: Depth,
): void {
  const header = prefix ? formatKeyedArrayHeader(prefix, items.length) : formatArrayHeader(items.length)
  writer.push(depth, header)

  for (const item of items) {
    if (isJsonPrimitive(item)) {
      // Direct primitive as list item
      writer.push(depth + 1, `${LIST_ITEM_PREFIX}${encodePrimitive(item)}`)
    }
    else if (isJsonArray(item)) {
      // Direct array as list item
      if (isArrayOfPrimitives(item)) {
        const inline = formatInlineArray(item)
        writer.push(depth + 1, `${LIST_ITEM_PREFIX}${inline}`)
      }
    }
    else if (isJsonObject(item)) {
      // Object as list item
      encodeObjectAsListItem(item, writer, depth + 1)
    }
  }
}

export function encodeArrayOfObjectsAsListItems(
  prefix: string | undefined,
  rows: readonly JsonObject[],
  writer: LineWriter,
  depth: Depth,
): void {
  const header = prefix ? formatKeyedArrayHeader(prefix, rows.length) : formatArrayHeader(rows.length)
  writer.push(depth, `${header}`)

  for (const obj of rows) {
    encodeObjectAsListItem(obj, writer, depth + 1)
  }
}

export function encodeObjectAsListItem(obj: JsonObject, writer: LineWriter, depth: Depth): void {
  const keys = Object.keys(obj)
  if (keys.length === 0) {
    writer.push(depth, LIST_ITEM_MARKER)
    return
  }

  // First key-value on the same line as "- "
  const firstKey = keys[0]!
  const encodedKey = encodeKey(firstKey)
  const firstValue = obj[firstKey]!

  if (isJsonPrimitive(firstValue)) {
    writer.push(depth, `${LIST_ITEM_PREFIX}${encodedKey}: ${encodePrimitive(firstValue)}`)
  }
  else if (isJsonArray(firstValue)) {
    // For arrays, we need to put them on separate lines
    writer.push(depth, `${LIST_ITEM_PREFIX}${encodedKey}[${firstValue.length}]:`)
    // ... handle array encoding (simplified for now)
  }
  else if (isJsonObject(firstValue)) {
    const nestedKeys = Object.keys(firstValue)
    if (nestedKeys.length === 0) {
      writer.push(depth, `${LIST_ITEM_PREFIX}${encodedKey}:`)
    }
    else {
      writer.push(depth, `${LIST_ITEM_PREFIX}${encodedKey}:`)
      encodeObject(firstValue, writer, depth + 2)
    }
  }

  // Remaining keys on indented lines
  for (let i = 1; i < keys.length; i++) {
    const key = keys[i]!
    encodeKeyValuePair(key, obj[key]!, writer, depth + 1)
  }
}

// #endregion