package binary

import (
	"errors"
	"strings"
)

// PKGInfo is the parsed content of an ALPM .PKGINFO file, the metadata
// member at the root of an Arch .pkg.tar.zst package.
type PKGInfo struct {
	Name, Version, Desc, URL, Arch                     string
	Depends, OptDepends, Provides, Conflicts, Replaces []string
}

// Parse parses ALPM .PKGINFO content: lines of "key = value", full-line
// `#` comments and blank lines ignored. Multi-value keys (depend,
// optdepend, provides, conflicts, replaces, license) accumulate across
// lines; single-value keys (pkgname, pkgver, pkgdesc, url, arch, pkgbase)
// take the last occurrence. pkgver is the FULL version, already in
// epoch+pkgrel form (e.g. "1.0-1" or "1:1.0.0-1"), and is passed through
// verbatim. Unknown keys are ignored. Malformed lines (no '=') are
// reported through warn and skipped, not fatal.
//
// Parse returns an error if pkgname is missing: a .PKGINFO without a name
// is invalid for conversion.
func Parse(src string, warn func(string)) (*PKGInfo, error) {
	info := &PKGInfo{}
	haveName := false
	for _, line := range strings.Split(src, "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		eq := strings.Index(line, "=")
		if eq < 0 {
			if warn != nil {
				warn("malformed .PKGINFO line (no '='): " + line)
			}
			continue
		}
		key := strings.TrimSpace(line[:eq])
		value := strings.TrimSpace(line[eq+1:])
		switch key {
		case "pkgname":
			info.Name = value
			haveName = true
		case "pkgver":
			info.Version = value
		case "pkgdesc":
			info.Desc = value
		case "url":
			info.URL = value
		case "arch":
			info.Arch = value
		case "depend":
			info.Depends = append(info.Depends, value)
		case "optdepend":
			info.OptDepends = append(info.OptDepends, value)
		case "provides":
			info.Provides = append(info.Provides, value)
		case "conflicts":
			info.Conflicts = append(info.Conflicts, value)
		case "replaces":
			info.Replaces = append(info.Replaces, value)
		default:
			// pkgbase, license, builddate, packager, size, xdata and any
			// unknown keys are not represented in PKGInfo; ignore them.
		}
	}
	if !haveName {
		return nil, errors.New("pkginfo: missing pkgname")
	}
	return info, nil
}