package runner

import (
	"encoding/json"
	"errors"
	"fmt"
	"git.0x7f.app/WOJ/woj-server/pkg/utils"
	"os"
	"path/filepath"
)

var (
	AllowedLanguages = map[string]struct {
		Interpreter string
	}{
		"c":       {""},
		"cpp":     {""},
		"go":      {""},
		"python3": {"/usr/bin/python3"},
		"pypy3":   {"/usr/bin/pypy3"},
		"rust":    {""},
	}
)

type ConfigRuntime struct {
	TimeLimit       int `json:"TimeLimit"`       // in ms
	MemoryLimit     int `json:"MemoryLimit"`     // in mb
	SoftMemoryLimit int `json:"SoftMemoryLimit"` // in mb
	NProcLimit      int `json:"NProcLimit"`
	WriteFileLimit  int `json:"WriteFileLimit"` // in mb
}

var (
	DefaultPrebuildRuntime = ConfigRuntime{
		TimeLimit:       300000,
		MemoryLimit:     256,
		SoftMemoryLimit: 256,
		NProcLimit:      64,
		WriteFileLimit:  1024,
	}
	DefaultCompileRuntime = ConfigRuntime{
		TimeLimit:       60000,
		MemoryLimit:     256,
		SoftMemoryLimit: 256,
		NProcLimit:      64,
		WriteFileLimit:  64,
	}
	DefaultCheckRuntime = ConfigRuntime{
		TimeLimit:       60000,
		MemoryLimit:     128,
		SoftMemoryLimit: 128,
		NProcLimit:      64,
		WriteFileLimit:  16,
	}
)

func (c *ConfigRuntime) InitWithDefault(fallback *ConfigRuntime) {
	if c.Validate() != nil {
		*c = *fallback
	} else {
		c.FillDefault()
	}
}

func (c *ConfigRuntime) FillDefault() {
	if c.SoftMemoryLimit <= 0 {
		// default to memory limit
		c.SoftMemoryLimit = c.MemoryLimit
	}
	if c.NProcLimit <= 0 {
		// default to not limited
		c.NProcLimit = 0
	}
	if c.WriteFileLimit <= 0 {
		// default to 1mb
		c.WriteFileLimit = 1
	}
}

func (c *ConfigRuntime) Validate() error {
	if c.TimeLimit <= 0 {
		return errors.New("time limit <= 0")
	}
	if c.MemoryLimit <= 0 {
		return errors.New("memory limit <= 0")
	}
	if c.SoftMemoryLimit <= 0 {
		// default to memory limit
		c.SoftMemoryLimit = c.MemoryLimit
	}
	if c.NProcLimit <= 0 {
		c.NProcLimit = 0
	}
	if c.WriteFileLimit <= 0 {
		// default to 1mb
		c.WriteFileLimit = 1
	}
	return nil
}

type ConfigJudge struct {
	Type   string `json:"Type"`
	Script string `json:"Script"`
	Cmp    string `json:"Cmp"`
}

func (c *ConfigJudge) Validate(base string, lang string) error {
	if c.Type != "custom" && c.Type != "default" {
		return fmt.Errorf("language %s has invalid type %s", lang, c.Type)
	}

	if c.Type == "custom" {
		if c.Script == "" {
			return fmt.Errorf("language %s has empty script", lang)
		}

		file := filepath.Join(base, "judge", c.Script)
		_, err := os.Stat(file)
		if err != nil {
			return fmt.Errorf("language %s has invalid script %s", lang, c.Script)
		}
	}

	if c.Type == "default" {
		if c.Cmp == "" {
			return fmt.Errorf("language %s has empty cmp", lang)
		}
	}

	return nil
}

type ConfigLanguage struct {
	Lang    string      `json:"Lang"`
	Judge   ConfigJudge `json:"Judge,omitempty"`
	Runtime struct {
		Compile ConfigRuntime `json:"Compile"`
		Run     ConfigRuntime `json:"Run"`
		Check   ConfigRuntime `json:"Check,omitempty"`
	} `json:"Runtime"`
}

func (l *ConfigLanguage) JudgeScript() string {
	if l.Judge.Type == "default" {
		return "/woj/framework/template/default/" + l.Lang + ".Makefile"
	} else {
		return "/woj/problem/judge/" + l.Judge.Script
	}
}

func (l *ConfigLanguage) JudgeInterpreter() string {
	return AllowedLanguages[l.Lang].Interpreter
}

type Config struct {
	Languages []ConfigLanguage `json:"Languages"`
	Prebuild  ConfigRuntime    `json:"Prebuild,omitempty"`
	Tasks     []struct {
		Id     int   `json:"Id"`
		Points int32 `json:"Points"`
	} `json:"Tasks"`
}

func (c *Config) Validate(base string) error {
	// check per language config
	for _, lang := range c.Languages {
		if _, ok := AllowedLanguages[lang.Lang]; !ok {
			return fmt.Errorf("language %s is not allowed", lang.Lang)
		}

		err := utils.NewMust().
			// check judge config
			Do(func() error { return lang.Judge.Validate(base, lang.Lang) }).
			// check runtime limits
			Do(func() error { return lang.Runtime.Compile.Validate() }).
			Do(func() error { return lang.Runtime.Run.Validate() }).
			Do(func() error { return lang.Runtime.Check.Validate() }).
			Done()

		if err != nil {
			return err
		}
	}

	// check prebuild config
	if err := c.Prebuild.Validate(); err != nil {
		return err
	}

	// check tasks

	if len(c.Tasks) == 0 {
		return errors.New("no tasks")
	}

	ids := map[int]struct{}{}
	total := (1 + len(c.Tasks)) * len(c.Tasks) / 2
	for _, task := range c.Tasks {
		if task.Id <= 0 {
			return fmt.Errorf("task %d has non-positive id", task.Id)
		}

		if task.Points < 0 {
			return fmt.Errorf("task %d has negative points", task.Id)
		}

		if _, ok := ids[task.Id]; ok {
			return fmt.Errorf("task %d has duplicate id", task.Id)
		}

		total -= task.Id
		ids[task.Id] = struct{}{}
	}
	if total != 0 {
		return errors.New("task ids are not continuous")
	}

	return nil
}

func (c *Config) FilterLanguage(lang string) (*ConfigLanguage, bool) {
	for idx := range c.Languages {
		if c.Languages[idx].Lang == lang {
			return &c.Languages[idx], true
		}
	}
	return &ConfigLanguage{}, false
}

func (s *service) ParseConfig(meta *JudgeMeta, skipCheck bool) (*Config, error) {
	base := filepath.Join(ProblemDir, fmt.Sprintf("%d", meta.Run.Version))
	file := filepath.Join(base, "config.json")

	data, err := os.ReadFile(file)
	if err != nil {
		return &Config{}, err
	}

	// unmarshal
	config := &Config{}
	err = json.Unmarshal(data, config)
	if err != nil {
		return &Config{}, err
	}

	// fill default
	for idx := range config.Languages {
		config.Languages[idx].Runtime.Compile.InitWithDefault(&DefaultCompileRuntime)
		config.Languages[idx].Runtime.Check.InitWithDefault(&DefaultCheckRuntime)
		config.Languages[idx].Runtime.Run.FillDefault()
	}
	config.Prebuild.InitWithDefault(&DefaultPrebuildRuntime)

	if skipCheck {
		return config, nil
	}

	err = config.Validate(base)
	if err != nil {
		return &Config{}, err
	}

	return config, nil
}