package main

import (
	"bufio"
	"fmt"
	"os"
	"path"
	"strings"
)

var infhcache = make(map[string]string, 1024)

func infh(name string) string {
	if s, ok := infhcache[name]; ok {
		return s
	}
	s := "    [" + name + "]"
	infhcache[name] = s
	return s
}

func scanHeader(name string, scan *bufio.Scanner) {
	ln := 0
	var regionfile *os.File
	symtab := symbolTable{
		"ZE_APICALL":   symbol{symbolTypeConst, "ZE_APICALL", []string{""}},
		"ZE_APIEXPORT": symbol{symbolTypeConst, "ZE_APIEXPORT", []string{""}},
		"ZE_DLLEXPORT": symbol{symbolTypeConst, "ZE_DLLEXPORT", []string{""}},
	}
	fileheadersb := strings.Builder{}
	region := ""
	for scan.Scan() {
		ln++
		t := scan.Text()
		switch {
		// file headers
		case strings.HasPrefix(t, "/*") || strings.HasPrefix(t, " *") || strings.HasPrefix(t, " */"):
			fileheadersb.WriteString(t)
			fileheadersb.WriteString("\n")
		// pragma start
		case strings.HasPrefix(t, "#pragma region "):
			region = strings.TrimSpace(t[15:])
			if region == "" {
				panic(fmt.Sprintf("%s L%d: unexpected empty region", name, ln))
			}
			fmt.Println(infh(name), "scanning region", region)
			_ = os.RemoveAll(name)
			err := os.MkdirAll(name, 0755)
			if err != nil {
				panic(fmt.Sprintf("%s L%d: cannot create region folder %s, err: %v", name, ln, region, err))
			}
			f, err := os.Create(path.Join(name, region+".go"))
			if err != nil {
				panic(fmt.Sprintf("%s L%d: cannot create region %s, err: %v", name, ln, region, err))
			}
			f.WriteString("// Code generated by gen. DO NOT EDIT.\n\n")
			f.WriteString(fileheadersb.String())
			f.WriteString("\n")
			f.WriteString("package ")
			f.WriteString(name)
			f.WriteString("\n\n")
			regionfile = f
		// block barrier
		case strings.HasPrefix(t, "///////////////////////////////////////////////////////////////////////////////"):
			fmt.Println("  [scan] enter", region, "block")
			ln = scanBlocks(name, scan, regionfile, ln, symtab)
			fmt.Println("  [scan] leave", region, "block")
		// pragma end
		case strings.HasPrefix(t, "#pragma endregion"):
			fmt.Println(infh(name), "close region", regionfile.Name())
			_ = regionfile.Close()
			regionfile = nil
		// skip outer #
		case strings.HasPrefix(t, "#") || t == "" || strings.HasPrefix(t, "// ") ||
			strings.HasPrefix(t, "extern "):
			fmt.Println("  [scan] skip", t)
			continue
		default:
			panic(fmt.Sprintf("%s L%d: unexpected line %s", name, ln, t))
		}
	}
}

func checkSymbolName(
	symtab symbolTable, ln int, name, sname, goname string,
	sb *strings.Builder, f *os.File, eq func() symbol) {
	if _, ok := symtab[sname]; ok {
		panic(fmt.Sprintf("%s L%d: func #define %s has been defined", name, ln, sname))
	}
	symtab[sname] = eq()
	if sb.Len() == 0 {
		panic(fmt.Sprintf("%s L%d: unexpected non-comment for symbol %s", name, ln, sname))
	}
	brief := " " + goname
	if goname != sname {
		brief = fmt.Sprint(brief, " (", sname, ")")
	}
	f.WriteString(strings.Replace(sb.String(), "/ @brief", brief, 1))
	sb.Reset()
}

func scanBlocks(
	name string, scan *bufio.Scanner, f *os.File,
	ln int, symtab symbolTable,
) int {
	sb := strings.Builder{}
	skip2nextblk := false //TODO: check logic
	ifdepth := 0
	isparsing := func() bool {
		//TODO: more condition
		return ifdepth > 0
	}
	for scan.Scan() {
		ln++
		t := scan.Text()
		switch {
		// block end
		case t == "":
			if isparsing() {
				continue
			}
			if sb.Len() != 0 {
				panic(fmt.Sprintf("%s L%d: unexpected non-0 sb at block end: %s", name, ln, &sb))
			}
			return ln
		case skip2nextblk:
			continue
		// is definition's comment
		case strings.HasPrefix(t, "/// "):
			sb.WriteString(t)
			sb.WriteString("\n")
		case strings.HasPrefix(t, "#if"):
			if len(t) <= 8 {
				panic(fmt.Sprintf("%s L%d: unexpected short #if", name, ln))
			}
			if t[3] == ' ' { // is platform related judgement
				skip2nextblk = true
				continue
			}
			if t[:8] != "#ifndef " {
				panic(fmt.Sprintf("%s L%d: unexpected #if type %s", name, ln, t))
			}
			sname := strings.TrimSpace(t[8:])
			_, ok := symtab[sname]
			if ok {
				ln = skip2endif(scan, ln)
				continue
			}
			ifdepth++
		case strings.HasPrefix(t, "#endif"):
			ifdepth--
			if ifdepth < 0 {
				panic(fmt.Sprintf("%s L%d: unexpected unpaired #endif", name, ln))
			}
		case strings.HasPrefix(t, "#define "):
			if !strings.Contains(t, "(") { // is const define
				argseval := trimEmptyStringArray(strings.Split(t[8:], " "))
				if len(argseval) != 2 {
					panic(fmt.Sprintf("%s L%d: unexpected const #define line %s", name, ln, t))
				}
				sname := strings.TrimSpace(argseval[0])
				val := strings.TrimSpace(argseval[1])
				checkSymbolName(symtab, ln, name, sname, sname, &sb, f, func() symbol {
					return newSymbolConst(sname, val)
				})
				f.WriteString("const ")
				f.WriteString(sname)
				f.WriteString(" = ")
				f.WriteString(val)
				f.WriteString("\n\n")
				continue
			}
			sname, argseval, ok := strings.Cut(t[8:], "(")
			if !ok {
				panic(fmt.Sprintf("%s L%d: unexpected #define line %s", name, ln, t))
			}
			args, n, err := getInsideRoundBrakets(argseval)
			if err != nil {
				panic(fmt.Sprintf("%s L%d: unexpected args bracket err: %v", name, ln, err))
			}
			sname = strings.TrimSpace(sname)
			args = strings.TrimSpace(args)
			eval := strings.TrimSpace(argseval[n+1:])
			checkSymbolName(symtab, ln, name, sname, sname, &sb, f, func() symbol {
				return newSymbolFunc(sname, args, eval)
			})
			f.WriteString("func ")
			f.WriteString(sname)
			f.WriteString("[T ~int | ~uint64 | ~uintptr](")
			f.WriteString(strings.Join(strings.Split(args, ","), " T,"))
			f.WriteString(" T) T {\n\treturn ")
			f.WriteString(eval)
			f.WriteString("\n}\n\n")
		case strings.HasPrefix(t, "typedef "):
			s, newln := get1sentence(t, scan, ln)
			if newln < 0 {
				panic(fmt.Sprintf("%s L%d: unexpected sentence end from", name, ln))
			}
			ln = newln
			typs := trimEmptyStringArray(strings.Split(s[8:], " "))
			if len(typs) == 0 {
				panic(fmt.Sprintf("%s L%d: unexpected typdef line %s", name, ln, t))
			}
			if strings.TrimSpace(typs[0]) == "struct" {
				if len(typs) != 3 || !strings.Contains(typs[1], "handle_t") ||
					!strings.Contains(typs[2], "*") {
					panic(fmt.Sprintf("%s L%d: unexpected typdef line %s", name, ln, t))
				}
				typs = typs[1:]
				typs[0] = "uintptr"
				typs[1] = strings.TrimPrefix(strings.TrimSpace(typs[1]), "*")
			}
			if len(typs) != 2 {
				panic(fmt.Sprintf("%s L%d: unexpected typdef line %s", name, ln, t))
			}
			sname := strings.TrimSpace(strings.TrimSuffix(strings.TrimSpace(typs[1]), ";"))
			val := us2camel(strings.TrimSuffix(sname, "_t"))
			origtyp := strings.TrimSuffix(strings.TrimSpace(typs[0]), "_t")
			checkSymbolName(symtab, ln, name, sname, val, &sb, f, func() symbol {
				return newSymbolConst(sname, val)
			})
			f.WriteString("type ")
			f.WriteString(val)
			f.WriteString(" ")
			f.WriteString(origtyp)
			f.WriteString("\n\n")
		}
	}
	return ln
}