package main

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

const (
	numbergenerics = "~int| ~uint32 | ~uint64 | ~uintptr"
)

var (
	typemap = map[string]string{
		"char":        "byte",
		"void*":       "unsafe.Pointer",
		"const void*": "unsafe.Pointer",
	}
)

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 := ""
	_ = 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))
	}
	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)
			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 cmd/gen. DO NOT EDIT.\n\n")
			f.WriteString(fileheadersb.String())
			f.WriteString("\n")
			f.WriteString("package ")
			f.WriteString(name)
			f.WriteString("\n\nimport (\n\t\"unsafe\"\n)\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) bool {
	if _, ok := symtab[sname]; ok {
		panic(fmt.Sprintf("%s L%d: func #define %s has been defined", name, ln, sname))
	}
	enumsname := strings.TrimSuffix(sname, "_t") + "s_t"
	if _, ok := symtab[enumsname]; ok {
		fmt.Println("[warn] redirect name", sname, "to", enumsname)
		return true
	}
	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()
	return false
}

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 {
				fmt.Printf("[warn] %s L%d: non-0 sb at block end: %s\n", 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 ")
			f.WriteString(numbergenerics)
			f.WriteString("](")
			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
			if strings.Contains(s, "\n") { // multi-line typedef
				lines := strings.Split(s, "\n")
				if len(lines) < 4 {
					panic(fmt.Sprintf("%s L%d: unexpected short multi typdef line %s", name, ln, t))
				}
				if lines[1] != "{" {
					panic(fmt.Sprintf("%s L%d: unexpected non-{ multi typdef line %s", name, ln, t))
				}
				switch {
				case strings.Contains(lines[0], " struct "):
					fsb := bytes.NewBuffer(make([]byte, 0, 256))
					for i, stat := range lines[2:] {
						if strings.HasPrefix(stat, "}") {
							lines = lines[2+i:]
							break
						}
						fsb.WriteString("\n")
						if stat == "" {
							continue
						}
						stat = strings.TrimSpace(stat)
						vname := ""
						c := ""
						switch {
						case strings.HasPrefix(stat, "char ") || strings.HasPrefix(stat, "void* ") ||
							strings.HasPrefix(stat, "const void*"):
							remains, sz := "", ""
							ok := false
							remains, c, ok = strings.Cut(stat, ";")
							if !ok {
								panic(fmt.Sprintf("%s L%d: unsupported non-end line %s", name, ln, stat))
							}
							c = strings.TrimPrefix(strings.TrimSpace(c), "//")
							remains = strings.TrimSpace(remains)
							i := strings.LastIndex(remains, " ")
							vname = remains[i+1:]
							tn := strings.TrimSpace(remains[:i])
							tname, ok := typemap[tn]
							if !ok {
								panic(fmt.Sprintf("%s L%d: unsupported type %s", name, ln, tname))
							}
							vname, sz, ok = strings.Cut(vname, "[")
							vname = us2camel(strings.TrimSpace(vname))
							fsb.WriteString("\t")
							if ok { // is array
								fsb.WriteString(vname)
								fsb.WriteString(" [")
								fsb.WriteString(sz)
								fsb.WriteString(tname)
							} else {
								fsb.WriteString(vname)
								fsb.WriteString(" ")
								fsb.WriteString(tname)
							}
						case strings.Contains(stat, "_t "):
							remains, sz := "", ""
							ok := false
							remains, c, ok = strings.Cut(stat, ";")
							if !ok {
								panic(fmt.Sprintf("%s L%d: unsupported non-end line %s", name, ln, stat))
							}
							c = strings.TrimPrefix(strings.TrimSpace(c), "//")
							tname, remains, ok := strings.Cut(remains, "_t ")
							if !ok {
								panic(fmt.Sprintf("%s L%d: unexpected statement %s", name, ln, stat))
							}
							tname = strings.TrimSpace(tname)
							k := tname + "_t"
							if symtab.contains(k) {
								tname = symtab[k].replace(k)
							}
							vname, sz, ok = strings.Cut(remains, "[")
							vname = us2camel(strings.TrimSpace(vname))
							fsb.WriteString("\t")
							if ok { // is array
								fsb.WriteString(vname)
								fsb.WriteString(" [")
								fsb.WriteString(sz)
								fsb.WriteString(tname)
							} else {
								fsb.WriteString(vname)
								fsb.WriteString(" ")
								fsb.WriteString(tname)
							}
						case strings.HasPrefix(stat, "///< "):
							fsb.Truncate(fsb.Len() - 1)
							fsb.WriteString(stat[4:])
						default:
							panic(fmt.Sprintf("%s L%d: unexpected statement %s", name, ln, stat))
						}
						if c != "" {
							fsb.WriteString("\t// ")
							fsb.WriteString(strings.Replace(c, "/<", vname, 1))
						}
					}
					if len(lines) != 1 {
						panic(fmt.Sprintf("%s L%d: unexpected len > 1 last lines %s", name, ln, strings.Join(lines, "\n")))
					}
					if !strings.HasPrefix(lines[0], "}") {
						panic(fmt.Sprintf("%s L%d: unexpected last line %s", name, ln, lines[0]))
					}
					sname := strings.TrimSuffix(strings.TrimSpace(lines[0][1:]), ";")
					val := us2camel(strings.TrimSuffix(sname, "_t"))
					checkSymbolName(symtab, ln, name, sname, val, &sb, f, func() *symbol {
						return newSymbolConst(sname, val)
					})
					f.WriteString("type ")
					f.WriteString(val)
					f.WriteString(" struct {")
					_, _ = io.Copy(f, fsb)
					f.WriteString("\n}\n\n")
					continue
				case strings.Contains(lines[0], " enum "):
					fsb := strings.Builder{}
					iscontinouscomment := false
					for i, stat := range lines[2:] {
						if strings.HasPrefix(stat, "}") {
							lines = lines[2+i:]
							break
						}
						fsb.WriteString("\n")
						if stat == "" {
							continue
						}
						stat = strings.TrimSpace(stat)
						if strings.HasPrefix(stat, "//") {
							if !iscontinouscomment {
								fsb.WriteString("\n")
							}
							fsb.WriteString("\t")
							fsb.WriteString(stat)
							iscontinouscomment = true
							continue
						}
						if iscontinouscomment {
							fsb.WriteString("\n")
						}
						iscontinouscomment = false
						constval, comment, ok := strings.Cut(stat, "//")
						if !ok {
							panic(fmt.Sprintf("%s L%d: unexpected enum line %s", name, ln, stat))
						}
						cname, _, _ := strings.Cut(constval, "=")
						fsb.WriteString("\t")
						fsb.WriteString(strings.TrimSuffix(strings.TrimSpace(constval), ","))
						fsb.WriteString("\t// ")
						fsb.WriteString(strings.Replace(comment, "/<", strings.TrimSpace(cname), 1))
					}
					if len(lines) != 1 {
						panic(fmt.Sprintf("%s L%d: unexpected len > 1 last lines %s", name, ln, strings.Join(lines, "\n")))
					}
					if !strings.HasPrefix(lines[0], "}") {
						panic(fmt.Sprintf("%s L%d: unexpected last line %s", name, ln, lines[0]))
					}
					sname := strings.TrimSuffix(strings.TrimSpace(lines[0][1:]), ";")
					val := us2camel(strings.TrimSuffix(sname, "_t"))
					redirect := checkSymbolName(symtab, ln, name, sname, val, &sb, f, func() *symbol {
						return newSymbolConst(sname, val)
					})
					replaces := ""
					if !redirect {
						f.WriteString("type ")
						f.WriteString(val)
						f.WriteString(" uintptr\nconst (")
						replaces = " " + val + " ="
					} else {
						_, _ = f.Seek(-1, io.SeekCurrent)
						f.WriteString("const (")
						replaces = " " + val + "s ="
					}
					vars := strings.ReplaceAll(fsb.String(), " =", replaces)
					if strings.Contains(vars, "(") {
						vars = symtab.apply(vars)
					}
					f.WriteString(vars)
					f.WriteString("\n)\n\n")
					continue
				}
			}
			// single-line typedef, empty struct or type alias, replace with "type" statement
			typs := trimEmptyStringArray(strings.Split(s[8:], " "))
			if len(typs) == 0 {
				panic(fmt.Sprintf("%s L%d: unexpected single 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], "*") {
					if symtab.contains(strings.TrimSuffix(typs[2], ";")) {
						fmt.Printf("[warn] %s L%d: skip duplicated single typdef %s\n", name, ln, strings.Join(typs, "_____"))
					} else {
						fmt.Printf("[warn] %s L%d: skip future expected single typdef %s\n", name, ln, strings.Join(typs, "_____"))
					}
					continue
				}
				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")
		default:
			panic(fmt.Sprintf("%s L%d: unexpected line %s", name, ln, t))
		}
	}
	return ln
}