package monitoring

import (
	"testing"

	"github.com/rcourtman/pulse-go-rewrite/pkg/proxmox"
)

func TestSelectVMAvailableFromMemInfo(t *testing.T) {
	giB := uint64(1024 * 1024 * 1024)
	miB := uint64(1024 * 1024)

	tests := []struct {
		name               string
		memInfo            *proxmox.VMMemInfo
		wantAvailable      uint64
		wantSource         string
		wantTotalMinusUsed uint64
	}{
		{
			name: "prefers explicit available",
			memInfo: &proxmox.VMMemInfo{
				Total:     16 * giB,
				Used:      10 * giB,
				Free:      2 * giB,
				Available: 6 * giB,
				Buffers:   512 * miB,
				Cached:    2 * giB,
			},
			wantAvailable:      6 * giB,
			wantSource:         "meminfo-available",
			wantTotalMinusUsed: 6 * giB,
		},
		{
			name: "uses derived free buffers cached when consistent",
			memInfo: &proxmox.VMMemInfo{
				Total:   8 * giB,
				Used:    4 * giB,
				Free:    1536 * miB,
				Buffers: 512 * miB,
				Cached:  2 * giB,
			},
			wantAvailable:      4 * giB,
			wantSource:         "meminfo-derived",
			wantTotalMinusUsed: 4 * giB,
		},
		{
			name: "defers derived when total-used gap is materially larger",
			memInfo: &proxmox.VMMemInfo{
				Total:   64 * giB,
				Used:    16 * giB,
				Free:    6 * giB,
				Buffers: 64 * miB,
				Cached:  128 * miB,
			},
			wantAvailable:      0,
			wantSource:         "",
			wantTotalMinusUsed: 48 * giB,
		},
		{
			name: "skips free-only meminfo and keeps total-used fallback",
			memInfo: &proxmox.VMMemInfo{
				Total: 32 * giB,
				Used:  22 * giB,
				Free:  10 * giB,
			},
			wantAvailable:      0,
			wantSource:         "",
			wantTotalMinusUsed: 10 * giB,
		},
		{
			name:    "nil meminfo",
			memInfo: nil,
		},
		{
			name: "keeps derived when gap is below tolerance",
			memInfo: &proxmox.VMMemInfo{
				Total:   1024 * miB,
				Used:    256 * miB,
				Free:    760 * miB,
				Buffers: 4 * miB,
			},
			wantAvailable:      764 * miB,
			wantSource:         "meminfo-derived",
			wantTotalMinusUsed: 768 * miB,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := selectVMAvailableFromMemInfo(tt.memInfo)
			if got.Available != tt.wantAvailable {
				t.Fatalf("available = %d, want %d", got.Available, tt.wantAvailable)
			}
			if got.Source != tt.wantSource {
				t.Fatalf("source = %q, want %q", got.Source, tt.wantSource)
			}
			if got.TotalMinusUsed != tt.wantTotalMinusUsed {
				t.Fatalf("totalMinusUsed = %d, want %d", got.TotalMinusUsed, tt.wantTotalMinusUsed)
			}
		})
	}
}

func TestSelectVMLowTrustUsedMemory(t *testing.T) {
	giB := uint64(1024 * 1024 * 1024)

	tests := []struct {
		name       string
		memTotal   uint64
		status     *proxmox.VMStatus
		wantUsed   uint64
		wantSource string
	}{
		{
			name:     "prefers status mem when it is plausible",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				Mem:     3 * giB,
				FreeMem: 5 * giB,
			},
			wantUsed:   3 * giB,
			wantSource: "status-mem",
		},
		{
			name:     "falls back to status freemem when status mem is falsely saturated",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				Mem:     8 * giB,
				FreeMem: 5 * giB,
			},
			wantUsed:   3 * giB,
			wantSource: "status-freemem",
		},
		{
			name:     "falls back to status freemem when status mem and freemem are materially inconsistent",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				Mem:     7920 * 1024 * 1024,
				FreeMem: 5 * giB,
			},
			wantUsed:   3 * giB,
			wantSource: "status-freemem",
		},
		{
			name:     "uses status freemem when status mem is absent",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				FreeMem: 6 * giB,
			},
			wantUsed:   2 * giB,
			wantSource: "status-freemem",
		},
		{
			name:     "uses balloon total when deriving used from status freemem",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				Balloon: 4 * giB,
				FreeMem: 1 * giB,
			},
			wantUsed:   3 * giB,
			wantSource: "status-freemem",
		},
		{
			name:     "uses balloon total when status mem is falsely saturated against balloon",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				Mem:     4 * giB,
				Balloon: 4 * giB,
				FreeMem: 1 * giB,
			},
			wantUsed:   3 * giB,
			wantSource: "status-freemem",
		},
		{
			name:       "returns empty selection without usable fields",
			memTotal:   8 * giB,
			status:     &proxmox.VMStatus{},
			wantUsed:   0,
			wantSource: "",
		},
		{
			name:     "keeps status mem when freemem only shows tiny headroom",
			memTotal: 8 * giB,
			status: &proxmox.VMStatus{
				Mem:     8*giB - (64 * 1024 * 1024),
				FreeMem: 64 * 1024 * 1024,
			},
			wantUsed:   8*giB - (64 * 1024 * 1024),
			wantSource: "status-mem",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := selectVMLowTrustUsedMemory(tt.memTotal, tt.status)
			if got.Used != tt.wantUsed {
				t.Fatalf("used = %d, want %d", got.Used, tt.wantUsed)
			}
			if got.Source != tt.wantSource {
				t.Fatalf("source = %q, want %q", got.Source, tt.wantSource)
			}
		})
	}
}