implement core logic (#3)

internal/adapters/ui/sort.go

@@ -0,0 +1,130 @@
+// Copyright 2025.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ui
+
+import (
+	"sort"
+	"strings"
+
+	"github.com/Adembc/lazyssh/internal/core/domain"
+)
+
+// SortMode controls how unpinned servers are ordered in the UI.
+type SortMode int
+
+const (
+	SortByAliasAsc SortMode = iota
+	SortByAliasDesc
+	SortByLastSeenDesc
+	SortByLastSeenAsc
+)
+
+func (m SortMode) String() string {
+	switch m {
+	case SortByAliasAsc:
+		return "Alias ↑"
+	case SortByAliasDesc:
+		return "Alias ↓"
+	case SortByLastSeenAsc:
+		return "Last SSH ↑"
+	case SortByLastSeenDesc:
+		return "Last SSH ↓"
+	default:
+		return "Alias ↑"
+	}
+}
+
+// ToggleField switches between Alias and LastSeen while preserving direction.
+func (m SortMode) ToggleField() SortMode {
+	switch m {
+	case SortByAliasAsc:
+		return SortByLastSeenAsc
+	case SortByAliasDesc:
+		return SortByLastSeenDesc
+	case SortByLastSeenAsc:
+		return SortByAliasAsc
+	case SortByLastSeenDesc:
+		return SortByAliasDesc
+	default:
+		return SortByAliasAsc
+	}
+}
+
+// Reverse flips the direction within the current field.
+func (m SortMode) Reverse() SortMode {
+	switch m {
+	case SortByAliasAsc:
+		return SortByAliasDesc
+	case SortByAliasDesc:
+		return SortByAliasAsc
+	case SortByLastSeenAsc:
+		return SortByLastSeenDesc
+	case SortByLastSeenDesc:
+		return SortByLastSeenAsc
+	default:
+		return SortByAliasAsc
+	}
+}
+
+// sortServersForUI sorts servers according to the rules required by the UI.
+// Pinned servers are always at the top, ordered by pinned date (newest first).
+// Unpinned servers are sorted by the selected mode. "Never" (zero time) goes to
+// the bottom when sorting by last seen asc/desc accordingly. Ties break by Alias asc.
+func sortServersForUI(servers []domain.Server, mode SortMode) {
+	sort.SliceStable(servers, func(i, j int) bool {
+		si, sj := servers[i], servers[j]
+
+		pi, pj := !si.PinnedAt.IsZero(), !sj.PinnedAt.IsZero()
+		if pi != pj {
+			return pi
+		}
+		if pi && pj { // both pinned: newer pinned first, tie-break alias
+			if !si.PinnedAt.Equal(sj.PinnedAt) {
+				return si.PinnedAt.After(sj.PinnedAt)
+			}
+			return strings.ToLower(si.Alias) < strings.ToLower(sj.Alias)
+		}
+
+		// both unpinned
+		switch mode {
+		case SortByLastSeenDesc, SortByLastSeenAsc:
+			zi := si.LastSeen.IsZero()
+			zj := sj.LastSeen.IsZero()
+			if zi != zj {
+				// when sorting by last seen, entries with zero (never) should be bottom in either direction
+				return !zi // non-zero first
+			}
+			if !zi && !zj && !si.LastSeen.Equal(sj.LastSeen) {
+				if mode == SortByLastSeenDesc {
+					return si.LastSeen.After(sj.LastSeen)
+				}
+				return si.LastSeen.Before(sj.LastSeen)
+			}
+			// tie-break by alias asc
+			return strings.ToLower(si.Alias) < strings.ToLower(sj.Alias)
+		case SortByAliasAsc:
+			return strings.ToLower(si.Alias) < strings.ToLower(sj.Alias)
+		case SortByAliasDesc:
+			ai := strings.ToLower(si.Alias)
+			aj := strings.ToLower(sj.Alias)
+			if ai != aj {
+				return ai > aj
+			}
+			return false
+		default:
+			return strings.ToLower(si.Alias) < strings.ToLower(sj.Alias)
+		}
+	})
+}