package ph7

/*
#include "cgo.h"
#include "ph7.h"
*/
import "C"
import (
	"fmt"
	"io"
	"unsafe"

	pointer "github.com/mattn/go-pointer"
)

type ResultCode int

const (
	ResultCodeOK         = ResultCode(C.PH7_OK)
	ResultCodeNoMem      = ResultCode(C.PH7_NOMEM)
	ResultCodeAbort      = ResultCode(C.PH7_ABORT)
	ResultCodeIOErr      = ResultCode(C.PH7_IO_ERR)
	ResultCodeLooked     = ResultCode(C.PH7_LOOKED)
	ResultCodeCorrupt    = ResultCode(C.PH7_CORRUPT)
	ResultCodeCompileErr = ResultCode(C.PH7_COMPILE_ERR)
	ResultCodeVMErr      = ResultCode(C.PH7_VM_ERR)
)

func (r ResultCode) String() string {
	switch r {
	case ResultCodeOK:
		return "PH7_OK"
	case ResultCodeNoMem:
		return "PH7_NOMEM"
	case ResultCodeAbort:
		return "PH7_ABORT"
	case ResultCodeIOErr:
		return "PH7_IO_ERR"
	case ResultCodeLooked:
		return "PH7_LOOKED"
	case ResultCodeCorrupt:
		return "PH7_CORRUPT"
	case ResultCodeCompileErr:
		return "PH7_COMPILE_ERR"
	case ResultCodeVMErr:
		return "PH7_VM_ERR"
	default:
		return "UNKNOWN"
	}
}

type Error struct {
	Code ResultCode
}

func newError(code C.int) error {
	if code == C.PH7_OK {
		return nil
	}
	return Error{
		Code: ResultCode(code),
	}
}

func (e Error) Error() string {
	return fmt.Sprintf("ph7: %s", e.Code.String())
}

type CompileError struct {
	Msg string
}

func (e CompileError) Error() string {
	return fmt.Sprintf("ph7 compile error: %s", e.Msg)
}

type Engine C.ph7

func NewEngine() (*Engine, error) {
	var cengine *C.ph7
	result := C.ph7_init(&cengine)
	if result != C.PH7_OK {
		return nil, newError(result)
	}

	return (*Engine)(cengine), nil
}

func (e *Engine) ErrLog() (string, error) {
	var s *C.char
	var n C.int

	err := newError(C.engine_config_err_log((*C.ph7)(e), &s, &n))
	if err != nil {
		return "", err
	}

	return C.GoStringN(s, n), nil
}

/*
We don't bother ph7_config verbs other than PH7_CONFIG_ERR_LOG.
PH7_CONFIG_ERR_OUTPUT is another way of getting compile error messages,
which we don't need separately from returning CompileError values.
PH7_CONFIG_ERR_ABORT doesn't do anything.
*/

func (e *Engine) compileError(code C.int) error {
	switch code {
	case C.PH7_OK:
		return nil
	case C.PH7_COMPILE_ERR:
		errLog, errLogErr := e.ErrLog()
		if errLogErr != nil || errLog == "" {
			return newError(code)
		}
		return CompileError{
			Msg: errLog,
		}
	default:
		return newError(code)
	}
}

func (e *Engine) Compile(source []byte, phpOnly bool) (*VM, error) {
	csource := C.CBytes(source)
	defer C.free(csource)
	var flags C.int
	if phpOnly {
		flags |= C.PH7_PHP_ONLY
	}
	var cvm *C.ph7_vm
	err := e.compileError(C.ph7_compile_v2((*C.ph7)(e), (*C.char)(csource), C.int(len(source)), &cvm, flags))
	if err != nil {
		return nil, err
	}

	return newVM(cvm), nil
}

func (e *Engine) CompileFile(path string, phpOnly bool) (*VM, error) {
	cpath := C.CString(path)
	defer C.free(unsafe.Pointer(cpath))

	var flags C.int
	if phpOnly {
		flags |= C.PH7_PHP_ONLY
	}
	var cvm *C.ph7_vm
	err := e.compileError(C.ph7_compile_file((*C.ph7)(e), cpath, &cvm, flags))
	if err != nil {
		return nil, err
	}

	return newVM(cvm), nil
}

func (e *Engine) Close() error {
	return newError(C.ph7_release((*C.ph7)(e)))
}

type Context C.ph7_context

func (c *Context) ResultInt(i int) error {
	return newError(C.ph7_result_int((*C.ph7_context)(c), C.int(i)))
}

func (c *Context) ResultInt64(i int64) error {
	return newError(C.ph7_result_int64((*C.ph7_context)(c), C.ph7_int64(i)))
}

func (c *Context) ResultBool(b bool) error {
	var cb C.int
	if b {
		cb = 1
	}
	return newError(C.ph7_result_bool((*C.ph7_context)(c), cb))
}

func (c *Context) ResultDouble(d float64) error {
	return newError(C.ph7_result_double((*C.ph7_context)(c), C.double(d)))
}

func (c *Context) ResultNull() error {
	return newError(C.ph7_result_null((*C.ph7_context)(c)))
}

func (c *Context) ResultString(s string) error {
	cs := C.CString(s)
	defer C.free(unsafe.Pointer(cs))

	return newError(C.ph7_result_string((*C.ph7_context)(c), cs, C.int(len(s))))
}

// TODO (*Context).ResultStringFormat maybe? Or just use fmt.Sprint*.

func (c *Context) ResultValue(value *Value) error {
	return newError(C.ph7_result_value((*C.ph7_context)(c), (*C.ph7_value)(value)))
}

// TODO (*Context).ResultResource

func (c *Context) Write(p []byte) (int, error) {
	cp := C.CBytes(p)
	defer C.free(cp)
	err := newError(C.ph7_context_output((*C.ph7_context)(c), (*C.char)(cp), C.int(len(p))))
	if err != nil {
		return 0, err
	}
	return len(p), nil
}

type Severity int

const (
	SeverityErr     Severity = C.PH7_CTX_ERR
	SeverityWarning Severity = C.PH7_CTX_WARNING
	SeverityNotice  Severity = C.PH7_CTX_NOTICE
)

func (c *Context) ThrowError(severity Severity, msg string) error {
	cmsg := C.CString(msg)
	defer C.free(unsafe.Pointer(cmsg))

	return newError(C.ph7_context_throw_error((*C.ph7_context)(c), C.int(severity), cmsg))
}

// TODO (*Context).ThrowErrorFormat maybe?

func (c *Context) RandomNum() uint {
	return uint(C.ph7_context_random_num((*C.ph7_context)(c)))
}

func (c *Context) RandomString(length int) (string, error) {
	buf := (*C.char)(C.malloc(C.size_t(length)))
	defer C.free(unsafe.Pointer(buf))

	err := newError(C.ph7_context_random_string((*C.ph7_context)(c), nil, C.int(length)))
	if err != nil {
		return "", err
	}
	return C.GoStringN(buf, C.int(length)), nil
}

// TODO (*Context).UserData
// TODO (*Context).PushAuxData
// TODO (*Context).PeekAuxData
// TODO (*Context).PopAuxData
// TODO (*Context).ResultBufLength
// TODO (*Context).FunctionName

// TODO (*Context).AllocChunk
// TODO (*Context).ReallocChunk
// TODO (*Context).FreeChunk

type Value C.ph7_value

func (v *Value) ToInt() int {
	return int(C.ph7_value_to_int((*C.ph7_value)(v)))
}

func (v *Value) ToBool() bool {
	return C.ph7_value_to_bool((*C.ph7_value)(v)) != 0
}

func (v *Value) ToInt64() int64 {
	return int64(C.ph7_value_to_int64((*C.ph7_value)(v)))
}

func (v *Value) ToDouble() float64 {
	return float64(C.ph7_value_to_double((*C.ph7_value)(v)))
}

func (v *Value) ToString() string {
	var strLen C.int
	cstr := C.ph7_value_to_string((*C.ph7_value)(v), &strLen)
	return C.GoStringN(cstr, strLen)
}

// TODO (*Value).ToResource

func (v *Value) Compare(v2 *Value) int {
	return int(C.ph7_value_compare((*C.ph7_value)(v), (*C.ph7_value)(v2), 0))
}

func (v *Value) CompareStrict(v2 *Value) int {
	return int(C.ph7_value_compare((*C.ph7_value)(v), (*C.ph7_value)(v2), 1))
}

// TODO (*Value).Int
// TODO (*Value).Int64
// TODO (*Value).Bool
// TODO (*Value).Null
// TODO (*Value).Double
// TODO (*Value).String
// TODO (*Value).StringFormat maybe?
// TODO (*Value).ResetStringCursor
// TODO (*Value).Resource
// TODO (*Value).Release
// TODO (*Value).ArrayFetch
// TODO (*Value).ArrayWalk
// TODO (*Value).ArrayAddElem
// TODO (*Value).ArrayAddStrkeyElem
// TODO (*Value).ArrayAddIntkeyElem
// TODO (*Value).ArrayCount
// TODO (*Value).ObjectWalk
// TODO (*Value).ObjectFetchAttr
// TODO (*Value).ObjectGetClassName

func (v *Value) IsInt() bool {
	return C.ph7_value_is_int((*C.ph7_value)(v)) != 0
}

func (v *Value) IsFloat() bool {
	return C.ph7_value_is_float((*C.ph7_value)(v)) != 0
}

func (v *Value) IsBool() bool {
	return C.ph7_value_is_bool((*C.ph7_value)(v)) != 0
}

func (v *Value) IsString() bool {
	return C.ph7_value_is_string((*C.ph7_value)(v)) != 0
}

func (v *Value) IsNull() bool {
	return C.ph7_value_is_null((*C.ph7_value)(v)) != 0
}

func (v *Value) IsNumeric() bool {
	return C.ph7_value_is_numeric((*C.ph7_value)(v)) != 0
}

func (v *Value) IsCallable() bool {
	return C.ph7_value_is_callable((*C.ph7_value)(v)) != 0
}

func (v *Value) IsScalar() bool {
	return C.ph7_value_is_scalar((*C.ph7_value)(v)) != 0
}

func (v *Value) IsArray() bool {
	return C.ph7_value_is_array((*C.ph7_value)(v)) != 0
}

func (v *Value) IsObject() bool {
	return C.ph7_value_is_object((*C.ph7_value)(v)) != 0
}

func (v *Value) IsResource() bool {
	return C.ph7_value_is_resource((*C.ph7_value)(v)) != 0
}

func (v *Value) IsEmpty() bool {
	return C.ph7_value_is_empty((*C.ph7_value)(v)) != 0
}

// ph7_lib_init is unnecessary when single-threaded, and possibly always.
// TODO Config
// TODO Shutdown
// TODO IsThreadsafe
// TODO Version
// TODO Signature
// TODO Ident
// TODO Copyright

type VM struct {
	ptr          *C.ph7_vm
	pointerKey   unsafe.Pointer
	outputWriter io.Writer
	// TODO clear outputWriteError when resetting VM
	outputWriteErr   error
	userFunctionKeys []unsafe.Pointer
}

func newVM(cvm *C.ph7_vm) *VM {
	vm := new(VM)
	vm.ptr = cvm
	vm.pointerKey = pointer.Save(vm)
	return vm
}

//export write_vm_output
func write_vm_output(buf unsafe.Pointer, bufLen C.uint, userData unsafe.Pointer) C.int {
	vm := pointer.Restore(userData).(*VM)
	gobuf := C.GoBytes(buf, C.int(bufLen))
	_, vm.outputWriteErr = vm.outputWriter.Write(gobuf)
	if vm.outputWriteErr != nil {
		return C.int(ResultCodeAbort)
	}
	return C.int(ResultCodeOK)
}

func (vm *VM) SetOutputWriter(w io.Writer) error {
	vm.outputWriter = w
	return newError(C.vm_set_output_callback(vm.ptr, vm.pointerKey))
}

// TODO PH7_VM_CONFIG_IMPORT_PATH
// TODO PH7_VM_CONFIG_RECURSION_DEPTH
// TODO PH7_VM_CONFIG_CREATE_SUPER
// TODO PH7_VM_CONFIG_CREATE_VAR
// TODO PH7_VM_CONFIG_HTTP_REQUEST
// TODO PH7_VM_CONFIG_SERVER_ATTR
// TODO PH7_VM_CONFIG_ENV_ATTR
// TODO PH7_VM_CONFIG_SESSION_ATTR
// TODO PH7_VM_CONFIG_POST_ATTR
// TODO PH7_VM_CONFIG_GET_ATTR
// TODO PH7_VM_CONFIG_COOKIE_ATTR
// TODO PH7_VM_CONFIG_HEADER_ATTR
// TODO PH7_VM_CONFIG_EXEC_VALUE
// TODO PH7_VM_CONFIG_IO_STREAM
// TODO PH7_VM_CONFIG_ARGV_ENTRY
// TODO PH7_VM_CONFIG_EXTRACT_OUTPUT
// TODO PH7_VM_CONFIG_ERR_LOG_HANDLER

// TODO (*VM).Dump(w io.Writer)

func (vm *VM) OutputWriteError() error {
	return vm.outputWriteErr
}

func (vm *VM) ReportErrors() error {
	return newError(C.vm_config_err_report((*C.ph7_vm)(vm.ptr)))
}

func (vm *VM) ExtractOutput() (string, error) {
	var s *C.char
	var n C.int

	err := newError(C.vm_extract_output(vm.ptr, &s, &n))
	if err != nil {
		return "", err
	}

	return C.GoStringN(s, n), nil
}

func (vm *VM) Exec() error {
	// TODO return exit status
	return newError(C.ph7_vm_exec(vm.ptr, (*C.int)(nil)))
}

func (vm *VM) Reset() error {
	return newError(C.ph7_vm_reset(vm.ptr))
}

func (vm *VM) Close() error {
	pointer.Unref(vm.pointerKey)
	for _, key := range vm.userFunctionKeys {
		pointer.Unref(key)
	}
	return newError(C.ph7_vm_release(vm.ptr))
}

type ForeignFunction interface {
	Call(ctx *Context, args []*Value) ResultCode
}

//export call_foreign_function
func call_foreign_function(ctx *C.ph7_context, argc C.int, argv **C.ph7_value) C.int {
	fkey := C.ph7_context_user_data(ctx)
	// TODO it looks like ph7 looks for a VFS at the user data pointer. WTF? Should we use it for that?
	f := pointer.Restore(fkey).(ForeignFunction)
	args := make([]*Value, 0, argc)
	argvSlice := unsafe.Slice(argv, argc)
	for i := range argvSlice {
		args = append(args, (*Value)(argvSlice[i]))
	}
	return C.int(f.Call((*Context)(ctx), args))
}

func (vm *VM) CreateFunction(name string, f ForeignFunction) error {
	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))

	fkey := pointer.Save(f)
	vm.userFunctionKeys = append(vm.userFunctionKeys, fkey)

	return newError(C.vm_create_function(vm.ptr, cname, fkey))
}

// TODO (*VM).DeleteFunction
// TODO (*VM).CreateConstant
// TODO (*VM).DeleteConstant