/**
 * `bun:ffi` lets you efficiently call C functions & FFI functions from JavaScript
 *  without writing bindings yourself.
 *
 * ```js
 * import {dlopen, CString, ptr} from 'bun:ffi';
 *
 * const lib = dlopen('libsqlite3', {
 * });
 * ```
 *
 * This is powered by just-in-time compiling C wrappers
 * that convert JavaScript types to C types and back. Internally,
 * bun uses [tinycc](https://github.com/TinyCC/tinycc), so a big thanks
 * goes to Fabrice Bellard and TinyCC maintainers for making this possible.
 *
 */
declare module "bun:ffi" {
  export enum FFIType {
    char = 0,
    /**
     * 8-bit signed integer
     *
     * Must be a value between -127 and 127
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * signed char
     * char // on x64 & aarch64 macOS
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    int8_t = 1,
    /**
     * 8-bit signed integer
     *
     * Must be a value between -127 and 127
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * signed char
     * char // on x64 & aarch64 macOS
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    i8 = 1,

    /**
     * 8-bit unsigned integer
     *
     * Must be a value between 0 and 255
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * unsigned char
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    uint8_t = 2,
    /**
     * 8-bit unsigned integer
     *
     * Must be a value between 0 and 255
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * unsigned char
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    u8 = 2,

    /**
     * 16-bit signed integer
     *
     * Must be a value between -32768 and 32767
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * in16_t
     * short // on arm64 & x64
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    int16_t = 3,
    /**
     * 16-bit signed integer
     *
     * Must be a value between -32768 and 32767
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * in16_t
     * short // on arm64 & x64
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    i16 = 3,

    /**
     * 16-bit unsigned integer
     *
     * Must be a value between 0 and 65535, inclusive.
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * uint16_t
     * unsigned short // on arm64 & x64
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    uint16_t = 4,
    /**
     * 16-bit unsigned integer
     *
     * Must be a value between 0 and 65535, inclusive.
     *
     * When passing to a FFI function (C ABI), type coercion is not performed.
     *
     * In C:
     * ```c
     * uint16_t
     * unsigned short // on arm64 & x64
     * ```
     *
     * In JavaScript:
     * ```js
     * var num = 0;
     * ```
     */
    u16 = 4,

    /**
     * 32-bit signed integer
     *
     */
    int32_t = 5,

    /**
     * 32-bit signed integer
     *
     * Alias of {@link FFIType.int32_t}
     */
    i32 = 5,
    /**
     * 32-bit signed integer
     *
     * The same as `int` in C
     *
     * ```c
     * int
     * ```
     */
    int = 5,

    /**
     * 32-bit unsigned integer
     *
     * The same as `unsigned int` in C (on x64 & arm64)
     *
     * C:
     * ```c
     * unsigned int
     * ```
     * JavaScript:
     * ```js
     * ptr(new Uint32Array(1))
     * ```
     */
    uint32_t = 6,
    /**
     * 32-bit unsigned integer
     *
     * Alias of {@link FFIType.uint32_t}
     */
    u32 = 6,

    /**
     * int64 is a 64-bit signed integer
     *
     * This is not implemented yet!
     */
    int64_t = 7,
    /**
     * i64 is a 64-bit signed integer
     *
     * This is not implemented yet!
     */
    i64 = 7,

    /**
     * 64-bit unsigned integer
     *
     * This is not implemented yet!
     */
    uint64_t = 8,
    /**
     * 64-bit unsigned integer
     *
     * This is not implemented yet!
     */
    u64 = 8,

    /**
     * Doubles are not supported yet!
     */
    double = 9,
    /**
     * Doubles are not supported yet!
     */
    f64 = 9,
    /**
     * Floats are not supported yet!
     */
    float = 10,
    /**
     * Floats are not supported yet!
     */
    f32 = 10,

    /**
     * Booelan value
     *
     * Must be `true` or `false`. `0` and `1` type coercion is not supported.
     *
     * In C, this corresponds to:
     * ```c
     * bool
     * _Bool
     * ```
     *
     *
     */
    bool = 11,

    /**
     * Pointer value
     *
     * See {@link Bun.FFI.ptr} for more information
     *
     * In C:
     * ```c
     * void*
     * ```
     *
     * In JavaScript:
     * ```js
     * ptr(new Uint8Array(1))
     * ```
     */
    ptr = 12,
    /**
     * Pointer value
     *
     * alias of {@link FFIType.ptr}
     */
    pointer = 12,

    /**
     * void value
     *
     * void arguments are not supported
     *
     * void return type is the default return type
     *
     * In C:
     * ```c
     * void
     * ```
     *
     */
    void = 13,

    /**
     * When used as a `returns`, this will automatically become a {@link CString}.
     *
     * When used in `args` it is equivalent to {@link FFIType.pointer}
     *
     */
    cstring = 14,

    /**
     * Attempt to coerce `BigInt` into a `Number` if it fits. This improves performance
     * but means you might get a `BigInt` or you might get a `number`.
     *
     * In C, this always becomes `int64_t`
     *
     * In JavaScript, this could be number or it could be BigInt, depending on what
     * value is passed in.
     *
     */
    i64_fast = 15,

    /**
     * Attempt to coerce `BigInt` into a `Number` if it fits. This improves performance
     * but means you might get a `BigInt` or you might get a `number`.
     *
     * In C, this always becomes `uint64_t`
     *
     * In JavaScript, this could be number or it could be BigInt, depending on what
     * value is passed in.
     *
     */
    u64_fast = 16,
  }
  export type FFITypeOrString =
    | FFIType
    | "char"
    | "int8_t"
    | "i8"
    | "uint8_t"
    | "u8"
    | "int16_t"
    | "i16"
    | "uint16_t"
    | "u16"
    | "int32_t"
    | "i32"
    | "int"
    | "uint32_t"
    | "u32"
    | "int64_t"
    | "i64"
    | "uint64_t"
    | "u64"
    | "double"
    | "f64"
    | "float"
    | "f32"
    | "bool"
    | "ptr"
    | "pointer"
    | "void"
    | "cstring"
    | "function";

  interface FFIFunction {
    /**
     * Arguments to a FFI function (C ABI)
     *
     * Defaults to an empty array, which means no arguments.
     *
     * To pass a pointer, use "ptr" or "pointer" as the type name. To get a pointer, see {@link ptr}.
     *
     * @example
     * From JavaScript:
     * ```js
     * const lib = dlopen('add', {
     *    // FFIType can be used or you can pass string labels.
     *    args: [FFIType.i32, "i32"],
     *    returns: "i32",
     * });
     * lib.symbols.add(1, 2)
     * ```
     * In C:
     * ```c
     * int add(int a, int b) {
     *   return a + b;
     * }
     * ```
     */
    args?: FFITypeOrString[];
    /**
     * Return type to a FFI function (C ABI)
     *
     * Defaults to {@link FFIType.void}
     *
     * To pass a pointer, use "ptr" or "pointer" as the type name. To get a pointer, see {@link ptr}.
     *
     * @example
     * From JavaScript:
     * ```js
     * const lib = dlopen('z', {
     *    version: {
     *      returns: "ptr",
     *   }
     * });
     * console.log(new CString(lib.symbols.version()));
     * ```
     * In C:
     * ```c
     * char* version()
     * {
     *  return "1.0.0";
     * }
     * ```
     */
    returns?: FFITypeOrString;

    /**
     * Function pointer to the native function
     *
     * If provided, instead of using dlsym() to lookup the function, Bun will use this instead.
     * This pointer should not be null (0).
     *
     * This is useful if the library has already been loaded
     * or if the module is also using Node-API.
     */
    ptr?: number | bigint;

    /**
     * Can C/FFI code call this function from a separate thread?
     *
     * Only supported with {@link JSCallback}.
     *
     * This does not make the function run in a separate thread. It is still up to the application/library
     * to run their code in a separate thread.
     *
     * By default, {@link JSCallback} calls are not thread-safe. Turning this on
     * incurs a small performance penalty for every function call. That small
     * performance penalty needs to be less than the performance gain from
     * running the function in a separate thread.
     *
     * @default false
     */
    threadsafe?: boolean;
  }

  type Symbols = Record<string, FFIFunction>;

  // /**
  //  * Compile a callback function
  //  *
  //  * Returns a function pointer
  //  *
  //  */
  // export function callback(ffi: FFIFunction, cb: Function): number;

  export interface Library {
    symbols: Record<
      string,
      CallableFunction & {
        /**
         * The function without a wrapper
         */
        native: CallableFunction;
      }
    >;

    /**
     * `dlclose` the library, unloading the symbols and freeing allocated memory.
     *
     * Once called, the library is no longer usable.
     *
     * Calling a function from a library that has been closed is undefined behavior.
     */
    close(): void;
  }

  /**
   * Open a library using `"bun:ffi"`
   *
   * @param name The name of the library or file path. This will be passed to `dlopen()`
   * @param symbols Map of symbols to load where the key is the symbol name and the value is the {@link FFIFunction}
   *
   * @example
   *
   * ```js
   * import {dlopen} from 'bun:ffi';
   *
   * const lib = dlopen("duckdb.dylib", {
   *   get_version: {
   *     returns: "cstring",
   *     args: [],
   *   },
   * });
   * lib.symbols.get_version();
   * // "1.0.0"
   * ```
   *
   * This is powered by just-in-time compiling C wrappers
   * that convert JavaScript types to C types and back. Internally,
   * bun uses [tinycc](https://github.com/TinyCC/tinycc), so a big thanks
   * goes to Fabrice Bellard and TinyCC maintainers for making this possible.
   *
   */
  export function dlopen(name: string, symbols: Symbols): Library;

  /**
   * Turn a native library's function pointer into a JavaScript function
   *
   * Libraries using Node-API & bun:ffi in the same module could use this to skip an extra dlopen() step.
   *
   * @param fn {@link FFIFunction} declaration. `ptr` is required
   *
   * @example
   *
   * ```js
   * import {CFunction} from 'bun:ffi';
   *
   * const getVersion = new CFunction({
   *   returns: "cstring",
   *   args: [],
   *   ptr: myNativeLibraryGetVersion,
   * });
   * getVersion();
   * getVersion.close();
   * ```
   *
   * This is powered by just-in-time compiling C wrappers
   * that convert JavaScript types to C types and back. Internally,
   * bun uses [tinycc](https://github.com/TinyCC/tinycc), so a big thanks
   * goes to Fabrice Bellard and TinyCC maintainers for making this possible.
   *
   */
  export function CFunction(
    fn: FFIFunction & { ptr: number | bigint },
  ): CallableFunction & {
    /**
     * Free the memory allocated by the wrapping function
     */
    close(): void;
  };

  /**
   * Link a map of symbols to JavaScript functions
   *
   * This lets you use native libraries that were already loaded somehow. You usually will want {@link dlopen} instead.
   *
   * You could use this with Node-API to skip loading a second time.
   *
   * @param symbols Map of symbols to load where the key is the symbol name and the value is the {@link FFIFunction}
   *
   * @example
   *
   * ```js
   * import { linkSymbols } from "bun:ffi";
   *
   * const [majorPtr, minorPtr, patchPtr] = getVersionPtrs();
   *
   * const lib = linkSymbols({
   *   // Unlike with dlopen(), the names here can be whatever you want
   *   getMajor: {
   *     returns: "cstring",
   *     args: [],
   *
   *     // Since this doesn't use dlsym(), you have to provide a valid ptr
   *     // That ptr could be a number or a bigint
   *     // An invalid pointer will crash your program.
   *     ptr: majorPtr,
   *   },
   *   getMinor: {
   *     returns: "cstring",
   *     args: [],
   *     ptr: minorPtr,
   *   },
   *   getPatch: {
   *     returns: "cstring",
   *     args: [],
   *     ptr: patchPtr,
   *   },
   * });
   *
   * const [major, minor, patch] = [
   *   lib.symbols.getMajor(),
   *   lib.symbols.getMinor(),
   *   lib.symbols.getPatch(),
   * ];
   * ```
   *
   * This is powered by just-in-time compiling C wrappers
   * that convert JavaScript types to C types and back. Internally,
   * bun uses [tinycc](https://github.com/TinyCC/tinycc), so a big thanks
   * goes to Fabrice Bellard and TinyCC maintainers for making this possible.
   *
   */
  export function linkSymbols(symbols: Symbols): Library;

  /**
   * Read a pointer as a {@link Buffer}
   *
   * If `byteLength` is not provided, the pointer is assumed to be 0-terminated.
   *
   * @param ptr The memory address to read
   * @param byteOffset bytes to skip before reading
   * @param byteLength bytes to read
   *
   * While there are some checks to catch invalid pointers, this is a difficult
   * thing to do safely. Passing an invalid pointer can crash the program and
   * reading beyond the bounds of the pointer will crash the program or cause
   * undefined behavior. Use with care!
   *
   */
  export function toBuffer(
    ptr: number,
    byteOffset?: number,
    byteLength?: number,
  ): Buffer;

  /**
   * Read a pointer as an {@link ArrayBuffer}
   *
   * If `byteLength` is not provided, the pointer is assumed to be 0-terminated.
   *
   * @param ptr The memory address to read
   * @param byteOffset bytes to skip before reading
   * @param byteLength bytes to read
   *
   * While there are some checks to catch invalid pointers, this is a difficult
   * thing to do safely. Passing an invalid pointer can crash the program and
   * reading beyond the bounds of the pointer will crash the program or cause
   * undefined behavior. Use with care!
   */
  export function toArrayBuffer(
    ptr: number,
    byteOffset?: number,
    byteLength?: number,
  ): ArrayBuffer;

  /**
   * Get the pointer backing a {@link TypedArray} or {@link ArrayBuffer}
   *
   * Use this to pass {@link TypedArray} or {@link ArrayBuffer} to C functions.
   *
   * This is for use with FFI functions. For performance reasons, FFI will
   * not automatically convert typed arrays to C pointers.
   *
   * @param {TypedArray|ArrayBuffer|DataView} view the typed array or array buffer to get the pointer for
   * @param {number} byteOffset optional offset into the view in bytes
   *
   * @example
   *
   * From JavaScript:
   * ```js
   * const array = new Uint8Array(10);
   * const rawPtr = ptr(array);
   * myFFIFunction(rawPtr);
   * ```
   * To C:
   * ```c
   * void myFFIFunction(char* rawPtr) {
   *  // Do something with rawPtr
   * }
   * ```
   *
   */
  export function ptr(
    view: TypedArray | ArrayBufferLike | DataView,
    byteOffset?: number,
  ): number;

  /**
   * Get a string from a UTF-8 encoded C string
   * If `byteLength` is not provided, the string is assumed to be null-terminated.
   *
   * @example
   * ```js
   * var ptr = lib.symbols.getVersion();
   * console.log(new CString(ptr));
   * ```
   *
   * @example
   * ```js
   * var ptr = lib.symbols.getVersion();
   * // print the first 4 characters
   * console.log(new CString(ptr, 0, 4));
   * ```
   *
   * While there are some checks to catch invalid pointers, this is a difficult
   * thing to do safely. Passing an invalid pointer can crash the program and
   * reading beyond the bounds of the pointer will crash the program or cause
   * undefined behavior. Use with care!
   */

  export class CString extends String {
    /**
     * Get a string from a UTF-8 encoded C string
     * If `byteLength` is not provided, the string is assumed to be null-terminated.
     *
     * @param ptr The pointer to the C string
     * @param byteOffset bytes to skip before reading
     * @param byteLength bytes to read
     *
     *
     * @example
     * ```js
     * var ptr = lib.symbols.getVersion();
     * console.log(new CString(ptr));
     * ```
     *
     * @example
     * ```js
     * var ptr = lib.symbols.getVersion();
     * // print the first 4 characters
     * console.log(new CString(ptr, 0, 4));
     * ```
     *
     * While there are some checks to catch invalid pointers, this is a difficult
     * thing to do safely. Passing an invalid pointer can crash the program and
     * reading beyond the bounds of the pointer will crash the program or cause
     * undefined behavior. Use with care!
     */
    constructor(ptr: number, byteOffset?: number, byteLength?: number);

    /**
     * The ptr to the C string
     *
     * This `CString` instance is a clone of the string, so it
     * is safe to continue using this instance after the `ptr` has been
     * freed.
     */
    ptr: number;
    byteOffset?: number;
    byteLength?: number;

    /**
     * Get the {@link ptr} as an `ArrayBuffer`
     *
     * `null` or empty ptrs returns an `ArrayBuffer` with `byteLength` 0
     */
    get arrayBuffer(): ArrayBuffer;
  }

  /**
   * Pass a JavaScript function to FFI (Foreign Function Interface)
   */
  export class JSCallback {
    /**
     * Enable a JavaScript callback function to be passed to C with bun:ffi
     *
     * @param callback The JavaScript function to be called
     * @param definition The C function definition
     */
    constructor(callback: (...args: any[]) => any, definition: FFIFunction);

    /**
     * The pointer to the C function
     *
     * Becomes `null` once {@link JSCallback.prototype.close} is called
     */
    readonly ptr: number | null;

    /**
     * Can the callback be called from a different thread?
     */
    readonly threadsafe: boolean;

    /**
     * Free the memory allocated for the callback
     *
     * If called multiple times, does nothing after the first call.
     */
    close(): void;
  }

  /**
   * View the generated C code for FFI bindings
   *
   * You probably won't need this unless there's a bug in the FFI bindings
   * generator or you're just curious.
   */
  export function viewSource(symbols: Symbols, is_callback?: false): string[];
  export function viewSource(callback: FFIFunction, is_callback: true): string;

  /**
   * Platform-specific file extension name for dynamic libraries
   *
   * "." is not included
   *
   * @example
   * ```js
   * "dylib" // macOS
   * ```
   *
   * @example
   * ```js
   * "so" // linux
   * ```
   */
  export const suffix: string;
}