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{""}},
	}
	for scan.Scan() {
		ln++
		t := scan.Text()
		switch {
		// 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\npackage ")
			f.WriteString(name)
			f.WriteString("\n")
			regionfile = f
		// block barrier
		case strings.HasPrefix(t, "///////////////////////////////////////////////////////////////////////////////"):
			regionfile.WriteString(t)
			regionfile.WriteString("\n")
			ln = scanblocks(name, scan, regionfile, ln, symtab)
		// pragma end
		case strings.HasPrefix(t, "#pragma endregion"):
			fmt.Println(infh(name), "close region", regionfile.Name())
			_ = regionfile.Close()
			regionfile = nil
		}
	}
}

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"):

		}
	}
	return ln
}