// Package mxutil holds the io/string helpers and target globals shared by
// the stage4 compiler packages (driver, types, ssa, emit).
package mxutil

import "unsafe"

//export write
func cWrite(fd int32, buf unsafe.Pointer, count uint32) (n int32)

//export mxc_readfile
func cReadfile(path unsafe.Pointer, pathLen int32, buf unsafe.Pointer, bufCap int32) (n int32)

//export mxc_filesize
func cFilesize(path unsafe.Pointer, pathLen int32) (n int32)

// Target triple components for the current compile.
var TargetOS string
var TargetArch string

// ImportSeg records one source file's import specs and the concat line its
// body starts at. The SSA builder uses this to give each file its own
// pkg-name scope: two files may bind the same local name to different
// packages, and the hoisted+deduped import block in the concat destroys
// that association.
type ImportSeg struct {
	OutStart int32
	Specs    []string // raw specs as written: `"path"` or `alias "path"`
}

var ConcatImportSegs []ImportSeg

func SetTarget(os, arch string) {
	TargetOS = os
	TargetArch = arch
}

func ResetConcatImportSegs() {
	ConcatImportSegs = nil
}

func AppendConcatImportSeg(seg ImportSeg) {
	push(ConcatImportSegs, seg)
}

func WriteStr(fd int32, s string) {
	if len(s) > 0 {
		cWrite(fd, unsafe.Pointer(unsafe.SliceData([]byte(s))), uint32(len(s)))
	}
}

func FileExists(path string) (ok bool) {
	if len(path) == 0 {
		return false
	}
	pp := unsafe.Pointer(unsafe.SliceData([]byte(path)))
	pl := int32(len(path))
	return cFilesize(pp, pl) >= 0
}

func ReadFile(path string) (data []byte, ok bool) {
	if len(path) == 0 {
		return nil, false
	}
	pp := unsafe.Pointer(unsafe.SliceData([]byte(path)))
	pl := int32(len(path))
	sz := cFilesize(pp, pl)
	if sz < 0 {
		return nil, false
	}
	if sz == 0 {
		sz = 65536
	}
	buf := []byte{:sz}
	n := cReadfile(pp, pl,
		unsafe.Pointer(unsafe.SliceData(buf)), sz)
	if n < 0 {
		return nil, false
	}
	return buf[:n], true
}

func SplitLines(s string) (ss []string) {
	var result []string
	start := int32(0)
	for i := int32(0); i < int32(len(s)); i++ {
		if s[i] == '\n' {
			if i > start {
				push(result, s[start:i])
			}
			start = i + 1
		}
	}
	if start < int32(len(s)) {
		push(result, s[start:])
	}
	return result
}

func HasPrefix(s, prefix string) (ok bool) {
	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
}

func HasSuffix(s, suffix string) (ok bool) {
	return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
}

func TrimSpace(s string) (sv string) {
	i := int32(0)
	for i < int32(len(s)) && (s[i] == ' ' || s[i] == '\t' || s[i] == '\n' || s[i] == '\r') {
		i++
	}
	j := int32(len(s))
	for j > i && (s[j-1] == ' ' || s[j-1] == '\t' || s[j-1] == '\n' || s[j-1] == '\r') {
		j--
	}
	return s[i:j]
}

func JoinPath(a, b string) (s string) {
	if len(a) == 0 {
		return b
	}
	if a[len(a)-1] == '/' {
		return a | b
	}
	return a | "/" | b
}

func ExtractQuoted(s string) (sv string) {
	start := int32(-1)
	for i := int32(0); i < int32(len(s)); i++ {
		if s[i] == '"' {
			if start < 0 {
				start = i + 1
			} else {
				return s[start:i]
			}
		}
	}
	return ""
}