package sqex

import (
	"fmt"
	"strings"
)

// PatchEntry is one row of Square Enix's patch list: the version a client
// reaches after applying it, and where to download it from.
type PatchEntry struct {
	VersionID string
	URL       string
}

// ParsePatchList parses the body SE's version server returns when the client
// needs updating (see auth.RegisterSession). The format mirrors what
// FFXIVQuickLauncher's PatchListParser expects: five header lines, then one
// tab-separated row per patch — length, three reserved fields, version id,
// hash type and either the URL (6 fields) or block size + hashes + URL
// (9 fields) — followed by two footer lines.
func ParsePatchList(text string) ([]PatchEntry, error) {
	lines := strings.Split(text, "\n")
	for i, l := range lines {
		lines[i] = strings.TrimSuffix(l, "\r")
	}
	if len(lines) < 7 {
		return nil, fmt.Errorf("patch list too short (%d lines)", len(lines))
	}

	var out []PatchEntry
	for _, line := range lines[5 : len(lines)-2] {
		if strings.TrimSpace(line) == "" {
			continue
		}
		f := strings.Split(line, "\t")
		if len(f) < 6 {
			return nil, fmt.Errorf("malformed patch list row: %q", line)
		}
		out = append(out, PatchEntry{VersionID: f[4], URL: f[len(f)-1]})
	}
	return out, nil
}

// TargetVersion returns the version a client reaches after applying all
// entries (the last one in list order), or "" for an empty list.
func TargetVersion(entries []PatchEntry) string {
	if len(entries) == 0 {
		return ""
	}
	return entries[len(entries)-1].VersionID
}