import {
  type ArraySchemaType,
  type MultiFieldSet,
  type ObjectField,
  type ObjectSchemaType,
  type Path,
  type SchemaType,
} from '@sanity/types'

import {getItemKeySegment, pathsAreEqual, pathToString} from '../../paths'
import {getArrayDiffItemType} from '../../schema/helpers'
import {
  type ArrayDiff,
  type ChangeNode,
  type ChangeTitlePath,
  type Diff,
  type DiffComponent,
  type FieldChangeNode,
  type ItemDiff,
  type ObjectDiff,
} from '../../types'
import {hasPTMemberType} from '../../types/portableText/diff/helpers'
import {getValueError} from '../../validation'
import {isFieldChange} from '../helpers'
import {resolveDiffComponent} from '../resolve/resolveDiffComponent'

interface DiffContext {
  itemDiff?: ItemDiff
  parentDiff?: ArrayDiff | ObjectDiff
  parentSchema?: ArraySchemaType | ObjectSchemaType
  fieldFilter?: string[]
}

export function buildChangeList(
  schemaType: SchemaType,
  diff: Diff,
  path: Path = [],
  titlePath: ChangeTitlePath = [],
  context: DiffContext = {},
): ChangeNode[] {
  const diffComponent = resolveDiffComponent(schemaType, context.parentSchema)

  if (!diffComponent) {
    if (schemaType.jsonType === 'object' && diff.type === 'object') {
      return buildObjectChangeList(schemaType as ObjectSchemaType, diff, path, titlePath, context)
    }

    if (schemaType.jsonType === 'array' && diff.type === 'array') {
      return buildArrayChangeList(schemaType, diff, path, titlePath)
    }
  }

  return getFieldChange(schemaType, diff, path, titlePath, context)
}

export function buildObjectChangeList(
  schemaType: ObjectSchemaType,
  diff: ObjectDiff,
  path: Path = [],
  titlePath: ChangeTitlePath = [],
  diffContext: DiffContext = {},
): ChangeNode[] {
  const changes: ChangeNode[] = []

  const childContext: DiffContext = {...diffContext, parentSchema: schemaType}
  const fieldSets =
    schemaType.fieldsets || schemaType.fields.map((field) => ({single: true, field}))
  for (const fieldSet of fieldSets) {
    if (fieldSet.single) {
      changes.push(...buildFieldChange(fieldSet.field, diff, path, titlePath, childContext))
    } else {
      changes.push(
        ...buildFieldsetChangeList(fieldSet as MultiFieldSet, diff, path, titlePath, childContext),
      )
    }
  }

  if (changes.length < 2) {
    return changes
  }

  return [
    {
      type: 'group',
      key: pathToString(path) || 'root',
      path,
      titlePath,
      changes: reduceTitlePaths(changes, titlePath.length),
      schemaType,
    },
  ]
}

export function buildFieldChange(
  field: ObjectField,
  diff: ObjectDiff,
  path: Path,
  titlePath: ChangeTitlePath,
  diffContext: DiffContext & {fieldFilter?: string[]} = {},
): ChangeNode[] {
  const {fieldFilter, ...context} = diffContext
  const fieldDiff = diff.fields[field.name]
  if (!fieldDiff || !fieldDiff.isChanged || (fieldFilter && !fieldFilter.includes(field.name))) {
    return []
  }

  const fieldPath = path.concat([field.name])
  const fieldTitlePath = titlePath.concat([field.type.title || field.name])
  return buildChangeList(field.type as any, fieldDiff, fieldPath, fieldTitlePath, context)
}

export function buildFieldsetChangeList(
  fieldSet: MultiFieldSet,
  diff: ObjectDiff,
  path: Path,
  titlePath: ChangeTitlePath,
  diffContext: DiffContext & {fieldFilter?: string[]} = {},
): ChangeNode[] {
  const {fields, name, title, readOnly, hidden} = fieldSet
  const {fieldFilter, ...context} = diffContext

  const fieldSetHidden = hidden
  const fieldsetReadOnly = readOnly

  const fieldSetTitlePath = titlePath.concat([title || name])
  const changes: ChangeNode[] = []

  for (const field of fields) {
    const fieldDiff = diff.fields[field.name]
    if (!fieldDiff || !fieldDiff.isChanged || (fieldFilter && !fieldFilter.includes(field.name))) {
      continue
    }

    const fieldPath = path.concat([field.name])
    const fieldTitlePath = fieldSetTitlePath.concat([field.type.title || field.name])
    changes.push(
      ...buildChangeList(
        {
          readOnly: fieldsetReadOnly,
          hidden: fieldSetHidden,
          ...field.type,
        } as any,
        fieldDiff,
        fieldPath,
        fieldTitlePath,
        context,
      ),
    )
  }

  if (changes.length < 2) {
    return changes
  }

  return [
    {
      type: 'group',
      key: pathToString(path) || 'root',
      fieldsetName: name,
      path,
      titlePath: fieldSetTitlePath,
      changes: reduceTitlePaths(changes, fieldSetTitlePath.length),
      readOnly: fieldsetReadOnly,
      hidden: fieldSetHidden,
    },
  ]
}

export function buildArrayChangeList(
  schemaType: ArraySchemaType,
  diff: ArrayDiff,
  path: Path = [],
  titlePath: ChangeTitlePath = [],
): ChangeNode[] {
  const changedOrMoved = diff.items.filter(
    (item) =>
      (item.hasMoved && item.fromIndex !== item.toIndex) || item.diff.action !== 'unchanged',
  )

  if (changedOrMoved.length === 0) {
    return []
  }

  const isPortableText = hasPTMemberType(schemaType)
  const list: ChangeNode[] = []
  const changes = changedOrMoved.reduce((acc, itemDiff) => {
    const memberTypes = getArrayDiffItemType(itemDiff.diff, schemaType)
    const memberType = memberTypes.toType || memberTypes.fromType
    if (!memberType) {
      // eslint-disable-next-line no-console
      console.warn('Could not determine schema type for item at %s', pathToString(path))
      return acc
    }

    const segment =
      getItemKeySegment(itemDiff.diff.fromValue) ||
      getItemKeySegment(itemDiff.diff.toValue) ||
      diff.items.indexOf(itemDiff)

    const itemPath = path.concat(segment)
    const itemContext: DiffContext = {itemDiff, parentDiff: diff, parentSchema: schemaType}
    const itemTitlePath = titlePath.concat({
      hasMoved: itemDiff.hasMoved,
      toIndex: itemDiff.toIndex,
      fromIndex: itemDiff.fromIndex,
      annotation:
        itemDiff.diff.action === 'unchanged' ? itemDiff.annotation : itemDiff.diff.annotation,
    })

    const attachItemDiff = (change: ChangeNode): ChangeNode => {
      if (change.type === 'field' && pathsAreEqual(itemPath, change.path)) {
        change.itemDiff = itemDiff
      }

      return change
    }

    const children = buildChangeList(
      memberType,
      itemDiff.diff,
      itemPath,
      itemTitlePath,
      itemContext,
    ).map(attachItemDiff)

    if (isPortableText) {
      children.filter(isFieldChange).forEach((field, index, siblings) => {
        field.showHeader = siblings.length === 1
        field.showIndex = itemDiff.fromIndex !== itemDiff.toIndex && itemDiff.hasMoved
      })
    }

    if (children.length === 0) {
      // This can happen when there are no changes to the actual element, it's just been moved
      acc.push(...getFieldChange(memberType, itemDiff.diff, itemPath, itemTitlePath, itemContext))
    } else {
      acc.push(...children)
    }

    return acc
  }, list)

  if (changes.length > 1) {
    return [
      {
        type: 'group',
        key: pathToString(path) || 'root',
        path,
        titlePath,
        changes: reduceTitlePaths(changes, titlePath.length),
        schemaType,
      },
    ]
  }

  return changes
}

function getFieldChange(
  schemaType: SchemaType,
  diff: Diff,
  path: Path,
  titlePath: ChangeTitlePath,
  {itemDiff, parentDiff, parentSchema}: DiffContext = {},
): FieldChangeNode[] {
  const {fromValue, toValue, type} = diff

  // Treat undefined => [] as no change
  if (type === 'array' && isEmpty(fromValue) && isEmpty(toValue)) {
    return []
  }

  let error
  if (typeof fromValue !== 'undefined') {
    error = getValueError(fromValue, schemaType)
  }

  if (!error && typeof toValue !== 'undefined') {
    error = getValueError(toValue, schemaType)
  }

  let showHeader = true
  let component: DiffComponent | undefined

  const diffComponent = resolveDiffComponent(schemaType, parentSchema)
  if (diffComponent && typeof diffComponent === 'function') {
    // Just a diff component with default options
    component = diffComponent
  } else if (diffComponent) {
    // Diff component with options
    component = (diffComponent as any).component
    showHeader =
      typeof (diffComponent as any).showHeader === 'undefined'
        ? showHeader
        : (diffComponent as any).showHeader
  }

  return [
    {
      type: 'field',
      diff,
      path,
      error,
      itemDiff,
      parentDiff,
      titlePath,
      schemaType,
      showHeader,
      showIndex: true,
      key: pathToString(path) || 'root',
      diffComponent: error ? undefined : component,
      parentSchema,
    },
  ]
}

function reduceTitlePaths(changes: ChangeNode[], byLength = 1): ChangeNode[] {
  return changes.map((change) => {
    change.titlePath = change.titlePath.slice(byLength)
    return change
  })
}

function isEmpty(item: unknown): boolean {
  return (Array.isArray(item) && item.length === 0) || item === null || typeof item === 'undefined'
}