package mjs

import (
	"context"
	"errors"
	"fmt"
	"log"
	"time"

	"git.ali33.ru/fcg-xvii/go-tools/cache"
	"github.com/dop251/goja"
)

func New(modified func(name string) int64, content func(name string) ([]byte, error)) *Mjs {
	return &Mjs{
		callbackModified: modified,
		callbackContent:  content,
		cache:            cache.NewCacheMap(context.Background(), 0, time.Hour*6),
	}
}

type Mjs struct {
	callbackModified func(name string) int64
	callbackContent  func(name string) ([]byte, error)
	cache            *cache.CacheMap
}

func (s *Mjs) program(name string) (prog *jsProgram, err error) {
	res, check := s.cache.GetCheck(name, func(key, val interface{}, exists bool) (rKey, rVal interface{}, needUpdate bool) {
		if exists {
			// check update need
			prog := val.(*jsProgram)
			// Why modified > prog.modified???
			if modified := s.callbackModified(name); modified == 0 || modified <= prog.modified {
				needUpdate = false
				return
			}
		}
		t := s.callbackModified(name)
		if t == 0 {
			err = fmt.Errorf("DOCUMENT %v NOT FOUND", name)
			return nil, nil, false
		}
		var content []byte
		if content, err = s.callbackContent(name); err != nil {
			return nil, nil, false
		}
		item := initProgram(name, string(content), t, s)
		return name, item, true
	})
	if check {
		prog = res.(*jsProgram)
		err = prog.compileErr
	} else {
		err = fmt.Errorf("Document %v is not defined", name)
	}
	return
}

func (s *Mjs) Exec(name string, data map[string]interface{}, durationMax time.Duration) (modified int64, err error) {

	defer func() {
		if err != nil && err.Error() == "<nil>" {
			err = nil
		}
		if r := recover(); r != nil && fmt.Sprint(r) != "runtime error: invalid memory address or nil pointer dereference" {
			err = fmt.Errorf("%v", r)
		}
	}()

	var prog *jsProgram
	if prog, err = s.program(name); err != nil {
		return
	}
	modified = prog.modified

	vm := goja.New()
	for k, v := range data {
		vm.Set(k, v)
	}

	if durationMax > 0 {
		time.AfterFunc(durationMax, func() {
			vm.Interrupt(fmt.Sprintf("Exec script timeout (%v sec.)", durationMax/time.Second))
		})
	}

	var incBefore []string
	mods, currentMod, parentMod := make(map[string]goja.Value), name, ""

	checkIncBefore := func(name string) bool {
		for _, v := range incBefore {
			if v == name {
				return true
			}
		}
		return false
	}

	getMod := func(name string) goja.Value {
		if parentMod == name {
			err = fmt.Errorf("include loop detected %v in module %v", name, name)
			return nil
		}
		if mod, check := mods[name]; check {
			return mod
		} else {
			if !checkIncBefore(name) {
				var prog *jsProgram
				if prog, err = s.program(name); err != nil {
					err = fmt.Errorf("%v in module %v", err, parentMod)
					vm.Interrupt(nil)
					return nil
				} else {
					if prog.modified > modified {
						modified = prog.modified
					}
					if _, sErr := vm.RunProgram(prog.prog); sErr == nil {
						incBefore = append(incBefore, name)
						return mods[name]
					} else if err == nil && sErr.Error() != "<nil>" {
						err = fmt.Errorf("%v in module %v", sErr, parentMod)
					}
					return nil
				}
			}
		}
		return nil
	}

	vm.Set("runtime", vm)

	vm.Set("log", func(vals ...interface{}) {
		log.Println(vals...)
	})

	vm.Set("define", func(vals ...interface{}) {
		fCall, tmp := goja.FunctionCall{}, currentMod
		parentMod = tmp
		for _, v := range vals {
			if call, check := v.(func(goja.FunctionCall) goja.Value); check {
				currentMod = tmp
				parentMod = currentMod
				mods[currentMod] = call(fCall)
				return
			} else {
				currentMod = fmt.Sprint(v)
				fCall.Arguments = append(fCall.Arguments, getMod(currentMod))
				if err != nil && err.Error() != "<nil>" {
					return
				}
			}
		}
	})

	vm.Set("require", func(vals ...interface{}) {
		fCall := goja.FunctionCall{}
		for _, v := range vals {
			if call, check := v.(func(goja.FunctionCall) goja.Value); check {
				call(fCall)
				return
			} else {
				currentMod = fmt.Sprint(v)
				fCall.Arguments = append(fCall.Arguments, getMod(currentMod))
				if err != nil {
					return
				}
			}
		}
	})

	vm.Set("initError", func(errText string) error {
		return errors.New(errText)
	})

	vm.Set("fileExists", func(path string) bool {
		return s.callbackModified(path) > 0
	})

	vm.Set("include", func(vals ...interface{}) {
		if len(vals) == 0 {
			return
		}
		name := fmt.Sprint(vals[0])
		params := make(map[string]interface{})
		if len(vals) == 2 {
			if m, check := vals[1].(map[string]interface{}); check {
				params = m
			}
		}
		var prog *jsProgram
		if prog, err = s.program(name); err == nil {
			tmp := currentMod
			currentMod = prog.name
			if prog.modified > modified {
				modified = prog.modified
			}
			current := make(map[string]interface{})
			for k, v := range params {
				if val := vm.Get(k); val != nil {
					current[k] = val
				}
				vm.Set(k, v)
			}
			if _, sErr := vm.RunProgram(prog.prog); sErr == nil {
				for k, _ := range params {
					if c, check := current[k]; check {
						vm.Set(k, c)
					} else {
						vm.Set(k, nil)
					}
				}
				currentMod = tmp
			} else if err == nil {
				err = sErr
				vm.Interrupt(nil)
			}
		} else {
			err = fmt.Errorf("%v in module %v", err, currentMod)
			vm.Interrupt(err)
		}
	})
	vm.Set("exit", func(vals ...interface{}) {
		vm.Interrupt(err)
	})
	vm.Set("sleep", func(msec int) {
		time.Sleep(time.Millisecond * time.Duration(msec))
	})
	if _, exErr := vm.RunProgram(prog.prog); exErr != nil && exErr.Error() != "<nil>" && err == nil {
		err = exErr
	}
	return
}