{-# LANGUAGE DuplicateRecordFields      #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE TemplateHaskell            #-}
module Language.Haskell.LSP.TH.Completion where

import qualified Data.Aeson                    as A
import           Data.Aeson.TH
import           Data.Text                      ( Text )
import           Language.Haskell.LSP.TH.Command
import           Language.Haskell.LSP.TH.Constants
import           Language.Haskell.LSP.TH.DocumentFilter
import           Language.Haskell.LSP.TH.List
import           Language.Haskell.LSP.TH.Message
import           Language.Haskell.LSP.TH.TextDocument
import           Language.Haskell.LSP.TH.Utils
import           Language.Haskell.LSP.TH.WorkspaceEdit

data CompletionItemKind = CiText
                        | CiMethod
                        | CiFunction
                        | CiConstructor
                        | CiField
                        | CiVariable
                        | CiClass
                        | CiInterface
                        | CiModule
                        | CiProperty
                        | CiUnit
                        | CiValue
                        | CiEnum
                        | CiKeyword
                        | CiSnippet
                        | CiColor
                        | CiFile
                        | CiReference
                        | CiFolder
                        | CiEnumMember
                        | CiConstant
                        | CiStruct
                        | CiEvent
                        | CiOperator
                        | CiTypeParameter
         deriving (Read,Show,Eq,Ord)

instance A.ToJSON CompletionItemKind where
  toJSON CiText          = A.Number 1
  toJSON CiMethod        = A.Number 2
  toJSON CiFunction      = A.Number 3
  toJSON CiConstructor   = A.Number 4
  toJSON CiField         = A.Number 5
  toJSON CiVariable      = A.Number 6
  toJSON CiClass         = A.Number 7
  toJSON CiInterface     = A.Number 8
  toJSON CiModule        = A.Number 9
  toJSON CiProperty      = A.Number 10
  toJSON CiUnit          = A.Number 11
  toJSON CiValue         = A.Number 12
  toJSON CiEnum          = A.Number 13
  toJSON CiKeyword       = A.Number 14
  toJSON CiSnippet       = A.Number 15
  toJSON CiColor         = A.Number 16
  toJSON CiFile          = A.Number 17
  toJSON CiReference     = A.Number 18
  toJSON CiFolder        = A.Number 19
  toJSON CiEnumMember    = A.Number 20
  toJSON CiConstant      = A.Number 21
  toJSON CiStruct        = A.Number 22
  toJSON CiEvent         = A.Number 23
  toJSON CiOperator      = A.Number 24
  toJSON CiTypeParameter = A.Number 25

instance A.FromJSON CompletionItemKind where
  parseJSON (A.Number  1) = pure CiText
  parseJSON (A.Number  2) = pure CiMethod
  parseJSON (A.Number  3) = pure CiFunction
  parseJSON (A.Number  4) = pure CiConstructor
  parseJSON (A.Number  5) = pure CiField
  parseJSON (A.Number  6) = pure CiVariable
  parseJSON (A.Number  7) = pure CiClass
  parseJSON (A.Number  8) = pure CiInterface
  parseJSON (A.Number  9) = pure CiModule
  parseJSON (A.Number 10) = pure CiProperty
  parseJSON (A.Number 11) = pure CiUnit
  parseJSON (A.Number 12) = pure CiValue
  parseJSON (A.Number 13) = pure CiEnum
  parseJSON (A.Number 14) = pure CiKeyword
  parseJSON (A.Number 15) = pure CiSnippet
  parseJSON (A.Number 16) = pure CiColor
  parseJSON (A.Number 17) = pure CiFile
  parseJSON (A.Number 18) = pure CiReference
  parseJSON (A.Number 19) = pure CiFolder
  parseJSON (A.Number 20) = pure CiEnumMember
  parseJSON (A.Number 21) = pure CiConstant
  parseJSON (A.Number 22) = pure CiStruct
  parseJSON (A.Number 23) = pure CiEvent
  parseJSON (A.Number 24) = pure CiOperator
  parseJSON (A.Number 25) = pure CiTypeParameter
  parseJSON _             = mempty


-- ---------------------------------------------------------------------
{-
Completion Request

The Completion request is sent from the client to the server to compute
completion items at a given cursor position. Completion items are presented in
the IntelliSense user interface. If computing full completion items is
expensive, servers can additionally provide a handler for the completion item
resolve request ('completionItem/resolve'). This request is sent when a
completion item is selected in the user interface. A typically use case is for
example: the 'textDocument/completion' request doesn't fill in the documentation
property for returned completion items since it is expensive to compute. When
the item is selected in the user interface then a 'completionItem/resolve'
request is sent with the selected completion item as a param. The returned
completion item should have the documentation property filled in.

    Changed: In 2.0 the request uses TextDocumentPositionParams with a proper
    textDocument and position property. In 1.0 the uri of the referenced text
    document was inlined into the params object.

Request

    method: 'textDocument/completion'
    params: TextDocumentPositionParams
-}

-- -------------------------------------

{-

Response

    result: CompletionItem[] | CompletionList

/**
 * Represents a collection of [completion items](#CompletionItem) to be presented
 * in the editor.
 */
interface CompletionList {
    /**
     * This list it not complete. Further typing should result in recomputing
     * this list.
     */
    isIncomplete: boolean;
    /**
     * The completion items.
     */
    items: CompletionItem[];
}


New in 3.0 : InsertTextFormat

/**
 * Defines whether the insert text in a completion item should be interpreted as
 * plain text or a snippet.
 */
namespace InsertTextFormat {
        /**
         * The primary text to be inserted is treated as a plain string.
         */
        export const PlainText = 1;

        /**
         * The primary text to be inserted is treated as a snippet.
         *
         * A snippet can define tab stops and placeholders with `$1`, `$2`
         * and `${3:foo}`. `$0` defines the final tab stop, it defaults to
         * the end of the snippet. Placeholders with equal identifiers are linked,
         * that is typing in one will update others too.
         *
         * See also: https://github.com/Microsoft/vscode/blob/master/src/vs/editor/contrib/snippet/common/snippet.md
         */
        export const Snippet = 2;
}



interface CompletionItem {
    /**
     * The label of this completion item. By default
     * also the text that is inserted when selecting
     * this completion.
     */
    label: string;
    /**
     * The kind of this completion item. Based of the kind
     * an icon is chosen by the editor.
     */
    kind?: number;
    /**
     * A human-readable string with additional information
     * about this item, like type or symbol information.
     */
    detail?: string;
    /**
     * A human-readable string that represents a doc-comment.
     */
    documentation?: string;
    /**
     * A string that shoud be used when comparing this item
     * with other items. When `falsy` the label is used.
     */
    sortText?: string;
    /**
     * A string that should be used when filtering a set of
     * completion items. When `falsy` the label is used.
     */
    filterText?: string;
    /**
     * A string that should be inserted a document when selecting
     * this completion. When `falsy` the label is used.
     */
    insertText?: string;
    -- Following field is new in 3.0
        /**
         * The format of the insert text. The format applies to both the `insertText` property
         * and the `newText` property of a provided `textEdit`.
         */
    insertTextFormat?: InsertTextFormat;
        /**
         * An edit which is applied to a document when selecting this completion. When an edit is provided the value of
         * `insertText` is ignored.
         *
         * *Note:* The range of the edit must be a single line range and it must contain the position at which completion
         * has been requested.
         */

    textEdit?: TextEdit;

    -- Following field is new in 3.0
        /**
         * An optional array of additional text edits that are applied when
         * selecting this completion. Edits must not overlap with the main edit
         * nor with themselves.
         */
    additionalTextEdits?: TextEdit[];
    -- Following field is new in 3.0
        /**
         * An optional command that is executed *after* inserting this completion. *Note* that
         * additional modifications to the current document should be described with the
         * additionalTextEdits-property.
         */

    command?: Command;
        /**
         * An data entry field that is preserved on a completion item between
         * a completion and a completion resolve request.
         */

    data?: any
}

Where CompletionItemKind is defined as follows:

/**
 * The kind of a completion entry.
 */
enum CompletionItemKind {
    Text = 1,
    Method = 2,
    Function = 3,
    Constructor = 4,
    Field = 5,
    Variable = 6,
    Class = 7,
    Interface = 8,
    Module = 9,
    Property = 10,
    Unit = 11,
    Value = 12,
    Enum = 13,
    Keyword = 14,
    Snippet = 15,
    Color = 16,
    File = 17,
    Reference = 18
}

    error: code and message set in case an exception happens during the completion request.
-}

-- -------------------------------------

data InsertTextFormat
  = PlainText -- ^The primary text to be inserted is treated as a plain string.
  | Snippet
      -- ^ The primary text to be inserted is treated as a snippet.
      --
      -- A snippet can define tab stops and placeholders with `$1`, `$2`
      -- and `${3:foo}`. `$0` defines the final tab stop, it defaults to
      -- the end of the snippet. Placeholders with equal identifiers are linked,
      -- that is typing in one will update others too.
      --
      -- See also: https://github.com/Microsoft/vscode/blob/master/src/vs/editor/contrib/snippet/common/snippet.md
    deriving (Show, Read, Eq)

instance A.ToJSON InsertTextFormat where
  toJSON PlainText = A.Number 1
  toJSON Snippet   = A.Number 2

instance A.FromJSON InsertTextFormat where
  parseJSON (A.Number  1) = pure PlainText
  parseJSON (A.Number  2) = pure Snippet
  parseJSON _             = mempty

data CompletionItem =
  CompletionItem
    { _label               :: Text -- ^ The label of this completion item. By default also
                       -- the text that is inserted when selecting this
                       -- completion.
    , _kind                :: Maybe CompletionItemKind
    , _detail              :: Maybe Text -- ^ A human-readable string with additional
                              -- information about this item, like type or
                              -- symbol information.
    , _documentation       :: Maybe Text -- ^ A human-readable string that represents
                                    -- a doc-comment.
    , _sortText            :: Maybe Text -- ^ A string that should be used when filtering
                                -- a set of completion items. When `falsy` the
                                -- label is used.
    , _filterText          :: Maybe Text -- ^ A string that should be used when
                                  -- filtering a set of completion items. When
                                  -- `falsy` the label is used.
    , _insertText          :: Maybe Text -- ^ A string that should be inserted a
                                  -- document when selecting this completion.
                                  -- When `falsy` the label is used.
    , _insertTextFormat    :: Maybe InsertTextFormat
         -- ^ The format of the insert text. The format applies to both the
         -- `insertText` property and the `newText` property of a provided
         -- `textEdit`.
    , _textEdit            :: Maybe TextEdit
         -- ^ An edit which is applied to a document when selecting this
         -- completion. When an edit is provided the value of `insertText` is
         -- ignored.
         --
         -- *Note:* The range of the edit must be a single line range and it
         -- must contain the position at which completion has been requested.
    , _additionalTextEdits :: Maybe (List TextEdit)
         -- ^ An optional array of additional text edits that are applied when
         -- selecting this completion. Edits must not overlap with the main edit
         -- nor with themselves.
    , _command             :: Maybe Command
        -- ^ An optional command that is executed *after* inserting this
        -- completion. *Note* that additional modifications to the current
        -- document should be described with the additionalTextEdits-property.
    , _xdata               :: Maybe A.Value -- ^ An data entry field that is preserved on a
                              -- completion item between a completion and a
                              -- completion resolve request.
    } deriving (Read,Show,Eq)

deriveJSON lspOptions{ fieldLabelModifier = customModifier } ''CompletionItem

data CompletionListType =
  CompletionListType
    { _isIncomplete :: Bool
    , _items        :: List CompletionItem
    } deriving (Read,Show,Eq)

deriveJSON lspOptions ''CompletionListType

data CompletionResponseResult
  = CompletionList CompletionListType
  | Completions (List CompletionItem)
  deriving (Read,Show,Eq)

deriveJSON defaultOptions { fieldLabelModifier = rdrop (length ("CompletionResponseResult"::String)), sumEncoding = UntaggedValue } ''CompletionResponseResult

type CompletionResponse = ResponseMessage CompletionResponseResult
type CompletionRequest = RequestMessage ClientMethod TextDocumentPositionParams CompletionResponseResult

-- -------------------------------------
{-
New in 3.0
-----------
Registration Options: CompletionRegistrationOptions options defined as follows:

export interface CompletionRegistrationOptions extends TextDocumentRegistrationOptions {
        /**
         * The characters that trigger completion automatically.
         */
        triggerCharacters?: string[];

        /**
         * The server provides support to resolve additional
         * information for a completion item.
         */
        resolveProvider?: boolean;
}
-}

data CompletionRegistrationOptions =
  CompletionRegistrationOptions
    { _documentSelector  :: Maybe DocumentSelector
    , _triggerCharacters :: Maybe (List String)
    , _resolveProvider   :: Maybe Bool
    } deriving (Show, Read, Eq)

deriveJSON lspOptions ''CompletionRegistrationOptions

-- ---------------------------------------------------------------------
{-
Completion Item Resolve Request

https://github.com/Microsoft/language-server-protocol/blob/master/protocol.md#completion-item-resolve-request

The request is sent from the client to the server to resolve additional
information for a given completion item.

Request

    method: 'completionItem/resolve'
    params: CompletionItem

Response

    result: CompletionItem
    error: code and message set in case an exception happens during the completion resolve request.
-}

type CompletionItemResolveRequest  = RequestMessage ClientMethod CompletionItem CompletionItem
type CompletionItemResolveResponse = ResponseMessage CompletionItem