import { tags } from "@angular-devkit/core"
import ts from "typescript"
import { Change, InsertChange, NoopChange } from "./change"

/**
 * Add Import `import { symbolName } from fileName` if the import doesn't exit
 * already. Assumes fileToEdit can be resolved and accessed.
 * @param fileToEdit (file we want to add import to)
 * @param symbolName (item to import)
 * @param fileName (path to the file)
 * @param isDefault (if true, import follows style for importing default exports)
 * @return Change
 */
export function insertImport(
  source: ts.SourceFile,
  fileToEdit: string,
  symbolName: string,
  fileName: string,
  isDefault = false
): Change {
  const rootNode = source
  const allImports = findNodes(rootNode, ts.SyntaxKind.ImportDeclaration)

  // get nodes that map to import statements from the file fileName
  const relevantImports = allImports.filter((node) => {
    // StringLiteral of the ImportDeclaration is the import file (fileName in this case).
    const importFiles = node
      .getChildren()
      .filter(ts.isStringLiteral)
      .map((n) => n.text)

    return importFiles.filter((file) => file === fileName).length === 1
  })

  if (relevantImports.length > 0) {
    let importsAsterisk = false
    // imports from import file
    const imports: ts.Node[] = []
    relevantImports.forEach((n) => {
      Array.prototype.push.apply(
        imports,
        findNodes(n, ts.SyntaxKind.Identifier)
      )
      if (findNodes(n, ts.SyntaxKind.AsteriskToken).length > 0) {
        importsAsterisk = true
      }
    })

    // if imports * from fileName, don't add symbolName
    if (importsAsterisk) {
      return new NoopChange()
    }

    const importTextNodes = imports.filter(
      (n) => (n as ts.Identifier).text === symbolName
    )

    // insert import if it's not there
    if (importTextNodes.length === 0) {
      const fallbackPos =
        findNodes(
          relevantImports[0],
          ts.SyntaxKind.CloseBraceToken
        )[0].getStart() ||
        findNodes(relevantImports[0], ts.SyntaxKind.FromKeyword)[0].getStart()

      return insertAfterLastOccurrence(
        imports,
        `, ${symbolName}`,
        fileToEdit,
        fallbackPos
      )
    }

    return new NoopChange()
  }

  // no such import declaration exists
  const useStrict = findNodes(rootNode, ts.isStringLiteral).filter(
    (n) => n.text === "use strict"
  )
  let fallbackPos = 0
  if (useStrict.length > 0) {
    fallbackPos = useStrict[0].end
  }
  const open = isDefault ? "" : "{ "
  const close = isDefault ? "" : " }"
  // if there are no imports or 'use strict' statement, insert import at beginning of file
  const insertAtBeginning = allImports.length === 0 && useStrict.length === 0
  const separator = insertAtBeginning ? "" : ";\n"
  const toInsert =
    `${separator}import ${open}${symbolName}${close}` +
    ` from '${fileName}'${insertAtBeginning ? ";\n" : ""}`

  return insertAfterLastOccurrence(
    allImports,
    toInsert,
    fileToEdit,
    fallbackPos,
    ts.SyntaxKind.StringLiteral
  )
}

/**
 * Find all nodes from the AST in the subtree of node of SyntaxKind kind.
 * @param node
 * @param kind
 * @param max The maximum number of items to return.
 * @param recursive Continue looking for nodes of kind recursive until end
 * the last child even when node of kind has been found.
 * @return all nodes of kind, or [] if none is found
 */
export function findNodes(
  node: ts.Node,
  kind: ts.SyntaxKind,
  max?: number,
  recursive?: boolean
): ts.Node[]

/**
 * Find all nodes from the AST in the subtree that satisfy a type guard.
 * @param node
 * @param guard
 * @param max The maximum number of items to return.
 * @param recursive Continue looking for nodes of kind recursive until end
 * the last child even when node of kind has been found.
 * @return all nodes that satisfy the type guard, or [] if none is found
 */
export function findNodes<T extends ts.Node>(
  node: ts.Node,
  guard: (node: ts.Node) => node is T,
  max?: number,
  recursive?: boolean
): T[]

export function findNodes<T extends ts.Node>(
  node: ts.Node,
  kindOrGuard: ts.SyntaxKind | ((node: ts.Node) => node is T),
  max = Infinity,
  recursive = false
): T[] {
  if (!node || max == 0) {
    return []
  }

  const test =
    typeof kindOrGuard === "function"
      ? kindOrGuard
      : (node: ts.Node): node is T => node.kind === kindOrGuard

  const arr: T[] = []
  if (test(node)) {
    arr.push(node)
    max--
  }
  if (max > 0 && (recursive || !test(node))) {
    for (const child of node.getChildren()) {
      findNodes(child, test, max, recursive).forEach((node) => {
        if (max > 0) {
          arr.push(node)
        }
        max--
      })

      if (max <= 0) {
        break
      }
    }
  }

  return arr
}

/**
 * Get all the nodes from a source.
 * @param sourceFile The source file object.
 * @returns {Array<ts.Node>} An array of all the nodes in the source.
 */
export function getSourceNodes(sourceFile: ts.SourceFile): ts.Node[] {
  const nodes: ts.Node[] = [sourceFile]
  const result = []

  while (nodes.length > 0) {
    const node = nodes.shift()

    if (node) {
      result.push(node)
      if (node.getChildCount(sourceFile) >= 0) {
        nodes.unshift(...node.getChildren())
      }
    }
  }

  return result
}

export function findNode(
  node: ts.Node,
  kind: ts.SyntaxKind,
  text: string
): ts.Node | null {
  if (node.kind === kind && node.getText() === text) {
    return node
  }

  let foundNode: ts.Node | null = null
  ts.forEachChild(node, (childNode) => {
    foundNode = foundNode || findNode(childNode, kind, text)
  })

  return foundNode
}

/**
 * Helper for sorting nodes.
 * @return function to sort nodes in increasing order of position in sourceFile
 */
function nodesByPosition(first: ts.Node, second: ts.Node): number {
  return first.getStart() - second.getStart()
}

/**
 * Insert `toInsert` after the last occurence of `ts.SyntaxKind[nodes[i].kind]`
 * or after the last of occurence of `syntaxKind` if the last occurence is a sub child
 * of ts.SyntaxKind[nodes[i].kind] and save the changes in file.
 *
 * @param nodes insert after the last occurence of nodes
 * @param toInsert string to insert
 * @param file file to insert changes into
 * @param fallbackPos position to insert if toInsert happens to be the first occurence
 * @param syntaxKind the ts.SyntaxKind of the subchildren to insert after
 * @return Change instance
 * @throw Error if toInsert is first occurence but fall back is not set
 */
export function insertAfterLastOccurrence(
  nodes: ts.Node[],
  toInsert: string,
  file: string,
  fallbackPos: number,
  syntaxKind?: ts.SyntaxKind
): Change {
  let lastItem: ts.Node | undefined
  for (const node of nodes) {
    if (!lastItem || lastItem.getStart() < node.getStart()) {
      lastItem = node
    }
  }
  if (syntaxKind && lastItem) {
    lastItem = findNodes(lastItem, syntaxKind).sort(nodesByPosition).pop()
  }
  if (!lastItem && fallbackPos == undefined) {
    throw new Error(
      `tried to insert ${toInsert} as first occurence with no fallback position`
    )
  }
  const lastItemPosition: number = lastItem ? lastItem.getEnd() : fallbackPos

  return new InsertChange(file, lastItemPosition, toInsert)
}

function _angularImportsFromNode(node: ts.ImportDeclaration): {
  [name: string]: string
} {
  const ms = node.moduleSpecifier
  let modulePath: string
  switch (ms.kind) {
    case ts.SyntaxKind.StringLiteral:
      modulePath = (ms as ts.StringLiteral).text
      break
    default:
      return {}
  }

  if (!modulePath.startsWith("@angular/")) {
    return {}
  }

  if (node.importClause) {
    if (node.importClause.name) {
      // This is of the form `import Name from 'path'`. Ignore.
      return {}
    } else if (node.importClause.namedBindings) {
      const nb = node.importClause.namedBindings
      if (nb.kind == ts.SyntaxKind.NamespaceImport) {
        // This is of the form `import * as name from 'path'`. Return `name.`.
        return {
          [nb.name.text + "."]: modulePath,
        }
      } else {
        // This is of the form `import {a,b,c} from 'path'`
        const namedImports = nb

        return namedImports.elements
          .map((is: ts.ImportSpecifier) =>
            is.propertyName ? is.propertyName.text : is.name.text
          )
          .reduce((acc: { [name: string]: string }, curr: string) => {
            acc[curr] = modulePath

            return acc
          }, {})
      }
    }

    return {}
  } else {
    // This is of the form `import 'path';`. Nothing to do.
    return {}
  }
}

export function getDecoratorMetadata(
  source: ts.SourceFile,
  identifier: string,
  module: string
): ts.Node[] {
  const angularImports = findNodes(source, ts.isImportDeclaration)
    .map((node) => _angularImportsFromNode(node))
    .reduce((acc, current) => {
      for (const key of Object.keys(current)) {
        acc[key] = current[key]
      }

      return acc
    }, {})

  return getSourceNodes(source)
    .filter((node) => {
      return (
        node.kind == ts.SyntaxKind.Decorator &&
        (node as ts.Decorator).expression.kind == ts.SyntaxKind.CallExpression
      )
    })
    .map((node) => (node as ts.Decorator).expression as ts.CallExpression)
    .filter((expr) => {
      if (expr.expression.kind == ts.SyntaxKind.Identifier) {
        const id = expr.expression as ts.Identifier

        return id.text == identifier && angularImports[id.text] === module
      } else if (
        expr.expression.kind == ts.SyntaxKind.PropertyAccessExpression
      ) {
        // This covers foo.NgModule when importing * as foo.
        const paExpr = expr.expression as ts.PropertyAccessExpression
        // If the left expression is not an identifier, just give up at that point.
        if (paExpr.expression.kind !== ts.SyntaxKind.Identifier) {
          return false
        }

        const id = paExpr.name.text
        const moduleId = (paExpr.expression as ts.Identifier).text

        return id === identifier && angularImports[moduleId + "."] === module
      }

      return false
    })
    .filter(
      (expr) =>
        expr.arguments[0] &&
        expr.arguments[0].kind == ts.SyntaxKind.ObjectLiteralExpression
    )
    .map((expr) => expr.arguments[0] as ts.ObjectLiteralExpression)
}

export function getMetadataField(
  node: ts.ObjectLiteralExpression,
  metadataField: string
): ts.ObjectLiteralElement[] {
  return (
    node.properties
      .filter(ts.isPropertyAssignment)
      // Filter out every fields that's not "metadataField". Also handles string literals
      // (but not expressions).
      .filter(({ name }) => {
        return (
          (ts.isIdentifier(name) || ts.isStringLiteral(name)) &&
          name.text === metadataField
        )
      })
  )
}

export function addSymbolToNgModuleMetadata(
  source: ts.SourceFile,
  ngModulePath: string,
  metadataField: string,
  symbolName: string,
  importPath: string | null = null
): Change[] {
  const nodes = getDecoratorMetadata(source, "NgModule", "@angular/core")
  const node = nodes[0]

  // Find the decorator declaration.
  if (!node || !ts.isObjectLiteralExpression(node)) {
    return []
  }

  // Get all the children property assignment of object literals.
  const matchingProperties = getMetadataField(node, metadataField)

  if (matchingProperties.length == 0) {
    // We haven't found the field in the metadata declaration. Insert a new field.
    let position: number
    let toInsert: string
    if (node.properties.length == 0) {
      position = node.getEnd() - 1
      toInsert = `\n  ${metadataField}: [\n${tags.indentBy(
        4
      )`${symbolName}`}\n  ]\n`
    } else {
      const childNode = node.properties[node.properties.length - 1]
      position = childNode.getEnd()
      // Get the indentation of the last element, if any.
      const text = childNode.getFullText(source)
      const matches = text.match(/^(\r?\n)(\s*)/)
      if (matches) {
        toInsert =
          `,${matches[0]}${metadataField}: [${matches[1]}` +
          `${tags.indentBy(matches[2].length + 2)`${symbolName}`}${matches[0]}]`
      } else {
        toInsert = `, ${metadataField}: [${symbolName}]`
      }
    }
    if (importPath !== null) {
      return [
        new InsertChange(ngModulePath, position, toInsert),
        insertImport(
          source,
          ngModulePath,
          symbolName.replace(/\..*$/, ""),
          importPath
        ),
      ];
    } else {
      return [new InsertChange(ngModulePath, position, toInsert)]
    }
  }
  const assignment = matchingProperties[0]

  // If it's not an array, nothing we can do really.
  if (
    !ts.isPropertyAssignment(assignment) ||
    !ts.isArrayLiteralExpression(assignment.initializer)
  ) {
    return []
  }

  let expresssion: ts.Expression | ts.ArrayLiteralExpression
  const assignmentInit = assignment.initializer
  const elements = assignmentInit.elements

  if (elements.length) {
    const symbolsArray = elements.map((node) => tags.oneLine`${node.getText()}`)
    if (symbolsArray.includes(tags.oneLine`${symbolName}`)) {
      return []
    }

    expresssion = elements[elements.length - 1]
  } else {
    expresssion = assignmentInit
  }

  let toInsert: string
  let position = expresssion.getEnd()
  if (ts.isArrayLiteralExpression(expresssion)) {
    // We found the field but it's empty. Insert it just before the `]`.
    position--
    toInsert = `\n${tags.indentBy(4)`${symbolName}`}\n  `
  } else {
    // Get the indentation of the last element, if any.
    const text = expresssion.getFullText(source)
    const matches = text.match(/^(\r?\n)(\s*)/)
    if (matches) {
      toInsert = `,${matches[1]}${tags.indentBy(
        matches[2].length
      )`${symbolName}`}`
    } else {
      toInsert = `, ${symbolName}`
    }
  }

  if (importPath !== null) {
    return [
      new InsertChange(ngModulePath, position, toInsert),
      insertImport(
        source,
        ngModulePath,
        symbolName.replace(/\..*$/, ""),
        importPath
      ),
    ];
  }

  return [new InsertChange(ngModulePath, position, toInsert)]
}

/**
 * Custom function to insert a declaration (component, pipe, directive)
 * into NgModule declarations. It also imports the component.
 */
export function addDeclarationToModule(
  source: ts.SourceFile,
  modulePath: string,
  classifiedName: string,
  importPath: string
): Change[] {
  return addSymbolToNgModuleMetadata(
    source,
    modulePath,
    "declarations",
    classifiedName,
    importPath
  )
}

/**
 * Custom function to insert an NgModule into NgModule imports. It also imports the module.
 */
export function addImportToModule(
  source: ts.SourceFile,
  modulePath: string,
  classifiedName: string,
  importPath: string
): Change[] {
  return addSymbolToNgModuleMetadata(
    source,
    modulePath,
    "imports",
    classifiedName,
    importPath
  )
}

/**
 * Custom function to insert a provider into NgModule. It also imports it.
 */
export function addProviderToModule(
  source: ts.SourceFile,
  modulePath: string,
  classifiedName: string,
  importPath: string
): Change[] {
  return addSymbolToNgModuleMetadata(
    source,
    modulePath,
    "providers",
    classifiedName,
    importPath
  )
}

/**
 * Custom function to insert an export into NgModule. It also imports it.
 */
export function addExportToModule(
  source: ts.SourceFile,
  modulePath: string,
  classifiedName: string,
  importPath: string
): Change[] {
  return addSymbolToNgModuleMetadata(
    source,
    modulePath,
    "exports",
    classifiedName,
    importPath
  )
}

/**
 * Custom function to insert an export into NgModule. It also imports it.
 */
export function addBootstrapToModule(
  source: ts.SourceFile,
  modulePath: string,
  classifiedName: string,
  importPath: string
): Change[] {
  return addSymbolToNgModuleMetadata(
    source,
    modulePath,
    "bootstrap",
    classifiedName,
    importPath
  )
}

/**
 * Determine if an import already exists.
 */
export function isImported(
  source: ts.SourceFile,
  classifiedName: string,
  importPath: string
): boolean {
  const allNodes = getSourceNodes(source)
  const matchingNodes = allNodes
    .filter(ts.isImportDeclaration)
    .filter(
      (imp) =>
        ts.isStringLiteral(imp.moduleSpecifier) &&
        imp.moduleSpecifier.text === importPath
    )
    .filter((imp) => {
      if (!imp.importClause) {
        return false
      }
      const nodes = findNodes(imp.importClause, ts.isImportSpecifier).filter(
        (n) => n.getText() === classifiedName
      )

      return nodes.length > 0
    })

  return matchingNodes.length > 0
}

/**
 * This function returns the name of the environment export
 * whether this export is aliased or not. If the environment file
 * is not imported, then it will return `null`.
 */
export function getEnvironmentExportName(source: ts.SourceFile): string | null {
  // Initial value is `null` as we don't know yet if the user
  // has imported `environment` into the root module or not.
  let environmentExportName: string | null = null

  const allNodes = getSourceNodes(source)

  allNodes
    .filter(ts.isImportDeclaration)
    .filter(
      (declaration) =>
        declaration.moduleSpecifier.kind === ts.SyntaxKind.StringLiteral &&
        declaration.importClause !== undefined
    )
    .map((declaration) =>
      // If `importClause` property is defined then the first
      // child will be `NamedImports` object (or `namedBindings`).
      (declaration.importClause as ts.ImportClause).getChildAt(0)
    )
    // Find those `NamedImports` object that contains `environment` keyword
    // in its text. E.g. `{ environment as env }`.
    .filter(ts.isNamedImports)
    .filter((namedImports) => namedImports.getText().includes("environment"))
    .forEach((namedImports) => {
      for (const specifier of namedImports.elements) {
        // `propertyName` is defined if the specifier
        // has an aliased import.
        const name = specifier.propertyName || specifier.name

        // Find specifier that contains `environment` keyword in its text.
        // Whether it's `environment` or `environment as env`.
        if (name.text.includes("environment")) {
          environmentExportName = specifier.name.text
        }
      }
    })

  return environmentExportName
}

/**
 * Returns the RouterModule declaration from NgModule metadata, if any.
 */
export function getRouterModuleDeclaration(
  source: ts.SourceFile
): ts.Expression | undefined {
  const result = getDecoratorMetadata(source, "NgModule", "@angular/core")
  const node = result[0]
  if (!node || !ts.isObjectLiteralExpression(node)) {
    return undefined
  }

  const matchingProperties = getMetadataField(node, "imports")
  if (!matchingProperties) {
    return
  }

  const assignment = matchingProperties[0] as ts.PropertyAssignment

  if (assignment.initializer.kind !== ts.SyntaxKind.ArrayLiteralExpression) {
    return
  }

  const arrLiteral = assignment.initializer as ts.ArrayLiteralExpression

  return arrLiteral.elements
    .filter((el) => el.kind === ts.SyntaxKind.CallExpression)
    .find((el) => (el as ts.Identifier).getText().startsWith("RouterModule"))
}

/**
 * Adds a new route declaration to a router module (i.e. has a RouterModule declaration)
 */
export function addRouteDeclarationToModule(
  source: ts.SourceFile,
  fileToAdd: string,
  routeLiteral: string
): Change {
  const routerModuleExpr = getRouterModuleDeclaration(source)
  if (!routerModuleExpr) {
    throw new Error(
      `Couldn't find a route declaration in ${fileToAdd}.\n` +
        `Use the '--module' option to specify a different routing module.`
    )
  }
  const scopeConfigMethodArgs = (routerModuleExpr as ts.CallExpression)
    .arguments
  if (!scopeConfigMethodArgs.length) {
    const { line } = source.getLineAndCharacterOfPosition(
      routerModuleExpr.getStart()
    )
    throw new Error(
      `The router module method doesn't have arguments ` +
        `at line ${line} in ${fileToAdd}`
    )
  }

  let routesArr: ts.ArrayLiteralExpression | undefined
  const routesArg = scopeConfigMethodArgs[0]

  // Check if the route declarations array is
  // an inlined argument of RouterModule or a standalone variable
  if (ts.isArrayLiteralExpression(routesArg)) {
    routesArr = routesArg
  } else {
    const routesVarName = routesArg.getText()
    let routesVar
    if (routesArg.kind === ts.SyntaxKind.Identifier) {
      routesVar = source.statements.filter(ts.isVariableStatement).find((v) => {
        return (
          v.declarationList.declarations[0].name.getText() === routesVarName
        )
      })
    }

    if (!routesVar) {
      const { line } = source.getLineAndCharacterOfPosition(
        routesArg.getStart()
      )
      throw new Error(
        `No route declaration array was found that corresponds ` +
          `to router module at line ${line} in ${fileToAdd}`
      )
    }

    routesArr = findNodes(
      routesVar,
      ts.SyntaxKind.ArrayLiteralExpression,
      1
    )[0] as ts.ArrayLiteralExpression
  }

  const occurrencesCount = routesArr.elements.length
  const text = routesArr.getFullText(source)

  let route: string = routeLiteral
  let insertPos = routesArr.elements.pos

  if (occurrencesCount > 0) {
    const lastRouteLiteral = [...routesArr.elements].pop() as ts.Expression
    const lastRouteIsWildcard =
      ts.isObjectLiteralExpression(lastRouteLiteral) &&
      lastRouteLiteral.properties.some(
        (n) =>
          ts.isPropertyAssignment(n) &&
          ts.isIdentifier(n.name) &&
          n.name.text === "path" &&
          ts.isStringLiteral(n.initializer) &&
          n.initializer.text === "**"
      )

    const indentation = text.match(/\r?\n(\r?)\s*/) || []
    const routeText = `${indentation[0] || " "}${routeLiteral}`

    // Add the new route before the wildcard route
    // otherwise we'll always redirect to the wildcard route
    if (lastRouteIsWildcard) {
      insertPos = lastRouteLiteral.pos
      route = `${routeText},`
    } else {
      insertPos = lastRouteLiteral.end
      route = `,${routeText}`
    }
  }

  return new InsertChange(fileToAdd, insertPos, route)
}