package runner

import (
	"fmt"
	"runtime"
	"sort"
	"strings"

	"github.com/Mond1c/judge/dsl"
)

type CompilerClass int

const (
	CompilerUnknown CompilerClass = iota
	CompilerGNU
	CompilerMSVC
)

type Toolchain struct {
	Class  CompilerClass
	Binary string
	Name   string
}

func ResolveToolchain(ccEnv string) Toolchain {
	if ccEnv == "" {
		ccEnv = defaultCC()
	}
	lower := strings.ToLower(ccEnv)
	switch lower {
	case "gcc", "g++":
		return Toolchain{Class: CompilerGNU, Binary: ccEnv, Name: "gcc"}
	case "clang", "clang++":
		return Toolchain{Class: CompilerGNU, Binary: ccEnv, Name: "clang"}
	case "cl", "cl.exe", "msvc":
		return Toolchain{Class: CompilerMSVC, Binary: "cl", Name: "msvc"}
	case "clang-cl", "clang-cl.exe":
		return Toolchain{Class: CompilerMSVC, Binary: "clang-cl", Name: "clang-cl"}
	case "cc":
		return Toolchain{Class: CompilerGNU, Binary: "cc", Name: "cc"}
	default:
		return Toolchain{Class: CompilerGNU, Binary: ccEnv, Name: lower}
	}
}

func ResolveToolchainSpec(spec *dsl.ToolchainSpec) Toolchain {
	inferred := ResolveToolchain(spec.Name)
	binary := spec.Binary
	if binary == "" {
		binary = inferred.Binary
	}
	var class CompilerClass
	switch spec.Class {
	case "gnu":
		class = CompilerGNU
	case "msvc":
		class = CompilerMSVC
	default:
		class = inferred.Class
	}
	return Toolchain{Class: class, Binary: binary, Name: spec.Name}
}

func defaultCC() string {
	if runtime.GOOS == "windows" {
		return "cl"
	}
	return "cc"
}

func Compile(cfg dsl.BuildConfig, tc Toolchain, outputPath string) ([]string, error) {
	switch tc.Class {
	case CompilerGNU:
		return compileGNU(cfg, tc, outputPath), nil
	case CompilerMSVC:
		return compileMSVC(cfg, tc, outputPath), nil
	default:
		return nil, fmt.Errorf("unknown compiler class for toolchain %q", tc.Name)
	}
}

func compileGNU(cfg dsl.BuildConfig, tc Toolchain, outputPath string) []string {
	argv := []string{tc.Binary}

	if cfg.Standard != "" {
		argv = append(argv, "-std="+cfg.Standard)
	}

	switch cfg.Profile {
	case dsl.ProfileRelease:
		argv = append(argv, "-O2")
	case dsl.ProfileDebug:
		argv = append(argv, "-O0", "-g")
	case dsl.ProfileSanitized:
		argv = append(argv, "-O1", "-g", "-fno-omit-frame-pointer")
	}

	switch cfg.Warnings {
	case dsl.WarningsStrict:
		argv = append(argv, "-Wall", "-Wextra")
	case dsl.WarningsPedantic:
		argv = append(argv, "-Wall", "-Wextra", "-Wpedantic")
	}

	if len(cfg.Sanitize) > 0 {
		argv = append(argv, "-fsanitize="+strings.Join(cfg.Sanitize, ","))
	}

	for _, inc := range cfg.Includes {
		argv = append(argv, "-I"+inc)
	}

	for _, k := range sortedKeys(cfg.Defines) {
		v := cfg.Defines[k]
		if v == "" {
			argv = append(argv, "-D"+k)
		} else {
			argv = append(argv, fmt.Sprintf("-D%s=%s", k, v))
		}
	}

	argv = append(argv, cfg.Extra...)
	argv = append(argv, cfg.Sources...)
	argv = append(argv, "-o", outputPath)

	for _, lib := range cfg.Link {
		argv = append(argv, "-l"+lib)
	}
	return argv
}

func compileMSVC(cfg dsl.BuildConfig, tc Toolchain, outputPath string) []string {
	argv := []string{tc.Binary, "/nologo"}

	if cfg.Standard != "" {
		argv = append(argv, "/std:"+cfg.Standard)
	}

	switch cfg.Profile {
	case dsl.ProfileRelease:
		argv = append(argv, "/O2")
	case dsl.ProfileDebug:
		argv = append(argv, "/Od", "/Zi")
	case dsl.ProfileSanitized:
		argv = append(argv, "/Od", "/Zi", "/fsanitize=address")
	}

	switch cfg.Warnings {
	case dsl.WarningsStrict:
		argv = append(argv, "/W4")
	case dsl.WarningsPedantic:
		argv = append(argv, "/W4", "/permissive-")
	}

	if containsString(cfg.Sanitize, "address") && cfg.Profile != dsl.ProfileSanitized {
		argv = append(argv, "/fsanitize=address")
	}

	for _, inc := range cfg.Includes {
		argv = append(argv, "/I"+inc)
	}

	for _, k := range sortedKeys(cfg.Defines) {
		v := cfg.Defines[k]
		if v == "" {
			argv = append(argv, "/D"+k)
		} else {
			argv = append(argv, fmt.Sprintf("/D%s=%s", k, v))
		}
	}

	argv = append(argv, cfg.Extra...)
	argv = append(argv, cfg.Sources...)
	argv = append(argv, "/Fe:"+outputPath)
	return argv
}

func sortedKeys(m map[string]string) []string {
	if len(m) == 0 {
		return nil
	}
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys
}

func containsString(xs []string, x string) bool {
	for _, v := range xs {
		if v == x {
			return true
		}
	}
	return false
}