import type * as atomIde from "atom-ide-base"
import Convert from "../convert"
import * as Utils from "../utils"
import { CancellationTokenSource } from "vscode-jsonrpc"
import {
  LanguageClientConnection,
  SymbolKind,
  ServerCapabilities,
  SymbolInformation,
  DocumentSymbol,
} from "../languageclient"
import { Point, TextEditor } from "atom"

/** Public: Adapts the documentSymbolProvider of the language server to the Outline View supplied by Atom IDE UI. */
export default class OutlineViewAdapter {
  private _cancellationTokens: WeakMap<LanguageClientConnection, CancellationTokenSource> = new WeakMap()

  /**
   * Public: Determine whether this adapter can be used to adapt a language server based on the serverCapabilities
   * matrix containing a documentSymbolProvider.
   *
   * @param serverCapabilities The {ServerCapabilities} of the language server to consider.
   * @returns A {Boolean} indicating adapter can adapt the server based on the given serverCapabilities.
   */
  public static canAdapt(serverCapabilities: ServerCapabilities): boolean {
    return serverCapabilities.documentSymbolProvider === true
  }

  /**
   * Public: Obtain the Outline for document via the {LanguageClientConnection} as identified by the {TextEditor}.
   *
   * @param connection A {LanguageClientConnection} to the language server that will be queried for the outline.
   * @param editor The Atom {TextEditor} containing the text the Outline should represent.
   * @returns A {Promise} containing the {Outline} of this document.
   */
  public async getOutline(connection: LanguageClientConnection, editor: TextEditor): Promise<atomIde.Outline | null> {
    const results = await Utils.doWithCancellationToken(connection, this._cancellationTokens, (cancellationToken) =>
      connection.documentSymbol({ textDocument: Convert.editorToTextDocumentIdentifier(editor) }, cancellationToken)
    )

    if (results === null || results.length === 0) {
      return {
        outlineTrees: [],
      }
    }

    if ((results[0] as DocumentSymbol).selectionRange !== undefined) {
      // If the server is giving back the newer DocumentSymbol format.
      return {
        outlineTrees: OutlineViewAdapter.createHierarchicalOutlineTrees(results as DocumentSymbol[]),
      }
    } else {
      // If the server is giving back the original SymbolInformation format.
      return {
        outlineTrees: OutlineViewAdapter.createOutlineTrees(results as SymbolInformation[]),
      }
    }
  }

  /**
   * Public: Create an {Array} of {OutlineTree}s from the Array of {DocumentSymbol} recieved from the language server.
   * This includes converting all the children nodes in the entire hierarchy.
   *
   * @param symbols An {Array} of {DocumentSymbol}s received from the language server that should be converted to an
   *   {Array} of {OutlineTree}.
   * @returns An {Array} of {OutlineTree} containing the given symbols that the Outline View can display.
   */
  public static createHierarchicalOutlineTrees(symbols: DocumentSymbol[]): atomIde.OutlineTree[] {
    // Sort all the incoming symbols
    symbols.sort((a, b) => {
      if (a.range.start.line !== b.range.start.line) {
        return a.range.start.line - b.range.start.line
      }

      if (a.range.start.character !== b.range.start.character) {
        return a.range.start.character - b.range.start.character
      }

      if (a.range.end.line !== b.range.end.line) {
        return a.range.end.line - b.range.end.line
      }

      return a.range.end.character - b.range.end.character
    })

    return symbols.map((symbol) => {
      const tree = OutlineViewAdapter.hierarchicalSymbolToOutline(symbol)

      if (symbol.children != null) {
        tree.children = OutlineViewAdapter.createHierarchicalOutlineTrees(symbol.children)
      }

      return tree
    })
  }

  /**
   * Public: Create an {Array} of {OutlineTree}s from the Array of {SymbolInformation} recieved from the language
   * server. This includes determining the appropriate child and parent relationships for the hierarchy.
   *
   * @param symbols An {Array} of {SymbolInformation}s received from the language server that should be converted to an
   *   {OutlineTree}.
   * @returns An {OutlineTree} containing the given symbols that the Outline View can display.
   */
  public static createOutlineTrees(symbols: SymbolInformation[]): atomIde.OutlineTree[] {
    symbols.sort((a, b) => {
      if (a.location.range.start.line === b.location.range.start.line) {
        return a.location.range.start.character - b.location.range.start.character
      } else {
        return a.location.range.start.line - b.location.range.start.line
      }
    })

    // Temporarily keep containerName through the conversion process
    // Also filter out symbols without a name - it's part of the spec but some don't include it
    const allItems = symbols
      .filter((symbol) => symbol.name)
      .map((symbol) => ({
        containerName: symbol.containerName,
        outline: OutlineViewAdapter.symbolToOutline(symbol),
      }))

    // Create a map of containers by name with all items that have that name
    const containers = allItems.reduce((map, item) => {
      const name = item.outline.representativeName
      if (name != null) {
        const container = map.get(name)
        if (container == null) {
          map.set(name, [item.outline])
        } else {
          container.push(item.outline)
        }
      }
      return map
    }, new Map())

    const roots: atomIde.OutlineTree[] = []

    // Put each item within its parent and extract out the roots
    for (const item of allItems) {
      const containerName = item.containerName
      const child = item.outline
      if (containerName == null || containerName === "") {
        roots.push(item.outline)
      } else {
        const possibleParents = containers.get(containerName)
        let closestParent = OutlineViewAdapter._getClosestParent(possibleParents, child)
        if (closestParent == null) {
          closestParent = {
            plainText: containerName,
            representativeName: containerName,
            startPosition: new Point(0, 0),
            children: [child],
          }
          roots.push(closestParent)
          if (possibleParents == null) {
            containers.set(containerName, [closestParent])
          } else {
            possibleParents.push(closestParent)
          }
        } else {
          closestParent.children.push(child)
        }
      }
    }

    return roots
  }

  private static _getClosestParent(
    candidates: atomIde.OutlineTree[] | null,
    child: atomIde.OutlineTree
  ): atomIde.OutlineTree | null {
    if (candidates == null || candidates.length === 0) {
      return null
    }

    let parent: atomIde.OutlineTree | undefined
    for (const candidate of candidates) {
      if (
        candidate !== child &&
        candidate.startPosition.isLessThanOrEqual(child.startPosition) &&
        (candidate.endPosition === undefined ||
          (child.endPosition && candidate.endPosition.isGreaterThanOrEqual(child.endPosition)))
      ) {
        if (
          parent === undefined ||
          parent.startPosition.isLessThanOrEqual(candidate.startPosition) ||
          (parent.endPosition != null &&
            candidate.endPosition &&
            parent.endPosition.isGreaterThanOrEqual(candidate.endPosition))
        ) {
          parent = candidate
        }
      }
    }

    return parent || null
  }

  /**
   * Public: Convert an individual {DocumentSymbol} from the language server to an {OutlineTree} for use by the Outline
   * View. It does NOT recursively process the given symbol's children (if any).
   *
   * @param symbol The {DocumentSymbol} to convert to an {OutlineTree}.
   * @returns The {OutlineTree} corresponding to the given {DocumentSymbol}.
   */
  public static hierarchicalSymbolToOutline(symbol: DocumentSymbol): atomIde.OutlineTree {
    const icon = OutlineViewAdapter.symbolKindToEntityKind(symbol.kind)

    return {
      tokenizedText: [
        {
          kind: OutlineViewAdapter.symbolKindToTokenKind(symbol.kind),
          value: symbol.name,
        },
      ],
      icon: icon != null ? icon : undefined,
      representativeName: symbol.name,
      startPosition: Convert.positionToPoint(symbol.selectionRange.start),
      endPosition: Convert.positionToPoint(symbol.selectionRange.end),
      children: [],
    }
  }

  /**
   * Public: Convert an individual {SymbolInformation} from the language server to an {OutlineTree} for use by the Outline View.
   *
   * @param symbol The {SymbolInformation} to convert to an {OutlineTree}.
   * @returns The {OutlineTree} equivalent to the given {SymbolInformation}.
   */
  public static symbolToOutline(symbol: SymbolInformation): atomIde.OutlineTree {
    const icon = OutlineViewAdapter.symbolKindToEntityKind(symbol.kind)
    return {
      tokenizedText: [
        {
          kind: OutlineViewAdapter.symbolKindToTokenKind(symbol.kind),
          value: symbol.name,
        },
      ],
      icon: icon != null ? icon : undefined,
      representativeName: symbol.name,
      startPosition: Convert.positionToPoint(symbol.location.range.start),
      endPosition: Convert.positionToPoint(symbol.location.range.end),
      children: [],
    }
  }

  /**
   * Public: Convert a symbol kind into an outline entity kind used to determine the styling such as the appropriate
   * icon in the Outline View.
   *
   * @param symbol The numeric symbol kind received from the language server.
   * @returns A string representing the equivalent OutlineView entity kind.
   */
  public static symbolKindToEntityKind(symbol: number): string | null {
    switch (symbol) {
      case SymbolKind.Array:
        return "type-array"
      case SymbolKind.Boolean:
        return "type-boolean"
      case SymbolKind.Class:
        return "type-class"
      case SymbolKind.Constant:
        return "type-constant"
      case SymbolKind.Constructor:
        return "type-constructor"
      case SymbolKind.Enum:
        return "type-enum"
      case SymbolKind.Field:
        return "type-field"
      case SymbolKind.File:
        return "type-file"
      case SymbolKind.Function:
        return "type-function"
      case SymbolKind.Interface:
        return "type-interface"
      case SymbolKind.Method:
        return "type-method"
      case SymbolKind.Module:
        return "type-module"
      case SymbolKind.Namespace:
        return "type-namespace"
      case SymbolKind.Number:
        return "type-number"
      case SymbolKind.Package:
        return "type-package"
      case SymbolKind.Property:
        return "type-property"
      case SymbolKind.String:
        return "type-string"
      case SymbolKind.Variable:
        return "type-variable"
      case SymbolKind.Struct:
        return "type-class"
      case SymbolKind.EnumMember:
        return "type-constant"
      default:
        return null
    }
  }

  /**
   * Public: Convert a symbol kind to the appropriate token kind used to syntax highlight the symbol name in the Outline View.
   *
   * @param symbol The numeric symbol kind received from the language server.
   * @returns A string representing the equivalent syntax token kind.
   */
  public static symbolKindToTokenKind(symbol: number): atomIde.TokenKind {
    switch (symbol) {
      case SymbolKind.Class:
        return "type"
      case SymbolKind.Constructor:
        return "constructor"
      case SymbolKind.Method:
      case SymbolKind.Function:
        return "method"
      case SymbolKind.String:
        return "string"
      default:
        return "plain"
    }
  }
}