package ast

import "github.com/evanw/esbuild/internal/logger"

// This file contains data structures that are used with the AST packages for
// both JavaScript and CSS. This helps the bundler treat both AST formats in
// a somewhat format-agnostic manner.

type ImportKind uint8

const (
	// An entry point provided by the user
	ImportEntryPoint ImportKind = iota

	// An ES6 import or re-export statement
	ImportStmt

	// A call to "require()"
	ImportRequire

	// An "import()" expression with a string argument
	ImportDynamic

	// A call to "require.resolve()"
	ImportRequireResolve

	// A CSS "@import" rule
	ImportAt

	// A CSS "@import" rule with import conditions
	ImportAtConditional

	// A CSS "url(...)" token
	ImportURL
)

func (kind ImportKind) StringForMetafile() string {
	switch kind {
	case ImportStmt:
		return "import-statement"
	case ImportRequire:
		return "require-call"
	case ImportDynamic:
		return "dynamic-import"
	case ImportRequireResolve:
		return "require-resolve"
	case ImportAt, ImportAtConditional:
		return "import-rule"
	case ImportURL:
		return "url-token"
	case ImportEntryPoint:
		return "entry-point"
	default:
		panic("Internal error")
	}
}

func (kind ImportKind) IsFromCSS() bool {
	return kind == ImportAt || kind == ImportURL
}

type ImportRecord struct {
	Range      logger.Range
	Path       logger.Path
	Assertions *[]AssertEntry

	// The resolved source index for an internal import (within the bundle) or
	// nil for an external import (not included in the bundle)
	SourceIndex Index32

	// Sometimes the parser creates an import record and decides it isn't needed.
	// For example, TypeScript code may have import statements that later turn
	// out to be type-only imports after analyzing the whole file.
	IsUnused bool

	// If this is true, the import contains syntax like "* as ns". This is used
	// to determine whether modules that have no exports need to be wrapped in a
	// CommonJS wrapper or not.
	ContainsImportStar bool

	// If this is true, the import contains an import for the alias "default",
	// either via the "import x from" or "import {default as x} from" syntax.
	ContainsDefaultAlias bool

	// If true, this "export * from 'path'" statement is evaluated at run-time by
	// calling the "__reExport()" helper function
	CallsRunTimeReExportFn bool

	// Tell the printer to wrap this call to "require()" in "__toESM(...)"
	WrapWithToESM bool

	// Tell the printer to wrap this ESM exports object in "__toCJS(...)"
	WrapWithToCJS bool

	// Tell the printer to use the runtime "__require()" instead of "require()"
	CallRuntimeRequire bool

	// True for the following cases:
	//
	//   try { require('x') } catch { handle }
	//   try { await import('x') } catch { handle }
	//   try { require.resolve('x') } catch { handle }
	//   import('x').catch(handle)
	//   import('x').then(_, handle)
	//
	// In these cases we shouldn't generate an error if the path could not be
	// resolved.
	HandlesImportErrors bool

	// If true, this was originally written as a bare "import 'file'" statement
	WasOriginallyBareImport bool

	Kind ImportKind
}

type AssertEntry struct {
	Key             []uint16 // An identifier or a string
	Value           []uint16 // Always a string
	KeyLoc          logger.Loc
	ValueLoc        logger.Loc
	PreferQuotedKey bool
}

// This stores a 32-bit index where the zero value is an invalid index. This is
// a better alternative to storing the index as a pointer since that has the
// same properties but takes up more space and costs an extra pointer traversal.
type Index32 struct {
	flippedBits uint32
}

func MakeIndex32(index uint32) Index32 {
	return Index32{flippedBits: ^index}
}

func (i Index32) IsValid() bool {
	return i.flippedBits != 0
}

func (i Index32) GetIndex() uint32 {
	return ^i.flippedBits
}