import type {
  CallExpression,
  Function as FunctionNode,
  Identifier,
  ImportExpression,
  Pattern,
  Property,
  VariableDeclaration,
  Node as _Node,
} from 'estree'
import { walk as eswalk } from 'estree-walker'

export type * from 'estree'

export type Positioned<T> = T & {
  start: number
  end: number
}

export type Node = Positioned<_Node>

interface IdentifierInfo {
  /**
   * If the identifier is used in a property shorthand
   * { foo } -> { foo: __import_x__.foo }
   */
  hasBindingShortcut: boolean
  /**
   * The identifier is used in a class declaration
   */
  classDeclaration: boolean
  /**
   * The identifier is a name for a class expression
   */
  classExpression: boolean
}

interface Visitors {
  onIdentifier?: (
    node: Positioned<Identifier>,
    info: IdentifierInfo,
    parentStack: Node[]
  ) => void
  onImportMeta?: (node: Node) => void
  onDynamicImport?: (node: Positioned<ImportExpression>) => void
  onCallExpression?: (node: Positioned<CallExpression>) => void
}

const isNodeInPatternWeakSet = new WeakSet<_Node>()
export function setIsNodeInPattern(node: Property) {
  return isNodeInPatternWeakSet.add(node)
}
export function isNodeInPattern(node: _Node): node is Property {
  return isNodeInPatternWeakSet.has(node)
}

/**
 * Same logic from \@vue/compiler-core & \@vue/compiler-sfc
 * Except this is using acorn AST
 */
export function esmWalker(
  root: Node,
  { onIdentifier, onImportMeta, onDynamicImport, onCallExpression }: Visitors,
) {
  const parentStack: Node[] = []
  const varKindStack: VariableDeclaration['kind'][] = []
  const scopeMap = new WeakMap<_Node, Set<string>>()
  const identifiers: [id: any, stack: Node[]][] = []

  const setScope = (node: _Node, name: string) => {
    let scopeIds = scopeMap.get(node)
    if (scopeIds && scopeIds.has(name)) {
      return
    }

    if (!scopeIds) {
      scopeIds = new Set()
      scopeMap.set(node, scopeIds)
    }
    scopeIds.add(name)
  }

  function isInScope(name: string, parents: Node[]) {
    return parents.some(node => node && scopeMap.get(node)?.has(name))
  }
  function handlePattern(p: Pattern, parentScope: _Node) {
    if (p.type === 'Identifier') {
      setScope(parentScope, p.name)
    }
    else if (p.type === 'RestElement') {
      handlePattern(p.argument, parentScope)
    }
    else if (p.type === 'ObjectPattern') {
      p.properties.forEach((property) => {
        if (property.type === 'RestElement') {
          setScope(parentScope, (property.argument as Identifier).name)
        }
        else {
          handlePattern(property.value, parentScope)
        }
      })
    }
    else if (p.type === 'ArrayPattern') {
      p.elements.forEach((element) => {
        if (element) {
          handlePattern(element, parentScope)
        }
      })
    }
    else if (p.type === 'AssignmentPattern') {
      handlePattern(p.left, parentScope)
    }
    else {
      setScope(parentScope, (p as any).name)
    }
  }

  eswalk(root, {
    enter(node, parent) {
      if (node.type === 'ImportDeclaration') {
        return this.skip()
      }

      // track parent stack, skip for "else-if"/"else" branches as acorn nests
      // the ast within "if" nodes instead of flattening them
      if (
        parent
        && !(parent.type === 'IfStatement' && node === parent.alternate)
      ) {
        parentStack.unshift(parent as Node)
      }

      // track variable declaration kind stack used by VariableDeclarator
      if (node.type === 'VariableDeclaration') {
        varKindStack.unshift(node.kind)
      }

      if (node.type === 'CallExpression') {
        onCallExpression?.(node as Positioned<CallExpression>)
      }

      if (node.type === 'MetaProperty' && node.meta.name === 'import') {
        onImportMeta?.(node as Node)
      }
      else if (node.type === 'ImportExpression') {
        onDynamicImport?.(node as Positioned<ImportExpression>)
      }

      if (node.type === 'Identifier') {
        if (
          !isInScope(node.name, parentStack)
          && isRefIdentifier(node, parent!, parentStack)
        ) {
          // record the identifier, for DFS -> BFS
          identifiers.push([node, parentStack.slice(0)])
        }
      }
      else if (isFunctionNode(node)) {
        // If it is a function declaration, it could be shadowing an import
        // Add its name to the scope so it won't get replaced
        if (node.type === 'FunctionDeclaration') {
          const parentScope = findParentScope(parentStack)
          if (parentScope) {
            setScope(parentScope, node.id!.name)
          }
        }
        // walk function expressions and add its arguments to known identifiers
        // so that we don't prefix them
        node.params.forEach((p) => {
          if (p.type === 'ObjectPattern' || p.type === 'ArrayPattern') {
            handlePattern(p, node)
            return
          }
          (eswalk as any)(p.type === 'AssignmentPattern' ? p.left : p, {
            enter(child: Node, parent: Node) {
              // skip params default value of destructure
              if (
                parent?.type === 'AssignmentPattern'
                && parent?.right === child
              ) {
                return this.skip()
              }

              if (child.type !== 'Identifier') {
                return
              }
              // do not record as scope variable if is a destructuring keyword
              if (isStaticPropertyKey(child, parent)) {
                return
              }
              // do not record if this is a default value
              // assignment of a destructuring variable
              if (
                (parent?.type === 'TemplateLiteral'
                && parent?.expressions.includes(child))
                || (parent?.type === 'CallExpression' && parent?.callee === child)
              ) {
                return
              }

              setScope(node, child.name)
            },
          })
        })
      }
      else if (node.type === 'Property' && parent!.type === 'ObjectPattern') {
        // mark property in destructuring pattern
        setIsNodeInPattern(node)
      }
      else if (node.type === 'VariableDeclarator') {
        const parentFunction = findParentScope(
          parentStack,
          varKindStack[0] === 'var',
        )
        if (parentFunction) {
          handlePattern(node.id, parentFunction)
        }
      }
      else if (node.type === 'CatchClause' && node.param) {
        handlePattern(node.param, node)
      }
    },

    leave(node, parent) {
      // untrack parent stack from above
      if (
        parent
        && !(parent.type === 'IfStatement' && node === parent.alternate)
      ) {
        parentStack.shift()
      }

      if (node.type === 'VariableDeclaration') {
        varKindStack.shift()
      }
    },
  })

  // emit the identifier events in BFS so the hoisted declarations
  // can be captured correctly
  identifiers.forEach(([node, stack]) => {
    if (!isInScope(node.name, stack)) {
      const parent = stack[0]
      const grandparent = stack[1]
      const hasBindingShortcut
        = isStaticProperty(parent)
        && parent.shorthand
        && (!isNodeInPattern(parent)
        || isInDestructuringAssignment(parent, parentStack))

      const classDeclaration
        = (parent.type === 'PropertyDefinition'
        && grandparent?.type === 'ClassBody')
        || (parent.type === 'ClassDeclaration' && node === parent.superClass)

      const classExpression
        = parent.type === 'ClassExpression' && node === parent.id

      onIdentifier?.(
        node,
        {
          hasBindingShortcut,
          classDeclaration,
          classExpression,
        },
        stack,
      )
    }
  })
}

function isRefIdentifier(id: Identifier, parent: _Node, parentStack: _Node[]) {
  // declaration id
  if (
    parent.type === 'CatchClause'
    || ((parent.type === 'VariableDeclarator'
    || parent.type === 'ClassDeclaration')
    && parent.id === id)
  ) {
    return false
  }

  if (isFunctionNode(parent)) {
    // function declaration/expression id
    if ((parent as any).id === id) {
      return false
    }

    // params list
    if (parent.params.includes(id)) {
      return false
    }
  }

  // class method name
  if (parent.type === 'MethodDefinition' && !parent.computed) {
    return false
  }

  // property key
  if (isStaticPropertyKey(id, parent)) {
    return false
  }

  // object destructuring pattern
  if (isNodeInPattern(parent) && parent.value === id) {
    return false
  }

  // non-assignment array destructuring pattern
  if (
    parent.type === 'ArrayPattern'
    && !isInDestructuringAssignment(parent, parentStack)
  ) {
    return false
  }

  // member expression property
  if (
    parent.type === 'MemberExpression'
    && parent.property === id
    && !parent.computed
  ) {
    return false
  }

  if (parent.type === 'ExportSpecifier') {
    return false
  }

  // is a special keyword but parsed as identifier
  if (id.name === 'arguments') {
    return false
  }

  return true
}

export function isStaticProperty(node: _Node): node is Property {
  return node && node.type === 'Property' && !node.computed
}

export function isStaticPropertyKey(node: _Node, parent: _Node) {
  return isStaticProperty(parent) && parent.key === node
}

const functionNodeTypeRE = /Function(?:Expression|Declaration)$|Method$/
export function isFunctionNode(node: _Node): node is FunctionNode {
  return functionNodeTypeRE.test(node.type)
}

const blockNodeTypeRE = /^BlockStatement$|^For(?:In|Of)?Statement$/
function isBlock(node: _Node) {
  return blockNodeTypeRE.test(node.type)
}

function findParentScope(
  parentStack: _Node[],
  isVar = false,
): _Node | undefined {
  return parentStack.find(isVar ? isFunctionNode : isBlock)
}

export function isInDestructuringAssignment(
  parent: _Node,
  parentStack: _Node[],
): boolean {
  if (
    parent
    && (parent.type === 'Property' || parent.type === 'ArrayPattern')
  ) {
    return parentStack.some(i => i.type === 'AssignmentExpression')
  }

  return false
}