package kvcache

import (
	"testing"

	"makarna/pkg/backend/cpu"
	"makarna/pkg/tensor"
)

func TestPagedKVCacheAppendViewsIncludeUncommitted(t *testing.T) {
	pool, err := NewBlockPool(BlockPoolConfig{
		NumLayers:  1,
		NumKVHeads: 1,
		HeadDim:    2,
		BlockSize:  4,
		NumBlocks:  4,
		Device:     tensor.CPU,
		GPU:        0,
	})
	if err != nil {
		t.Fatalf("NewBlockPool: %v", err)
	}
	cache := NewPagedKVCache(pool, PagedCacheConfig{
		NumLayers:  1,
		NumKVHeads: 1,
		HeadDim:    2,
		BlockSize:  4,
		MaxSeqLen:  16,
		Device:     tensor.CPU,
		GPU:        0,
	}, "req")
	defer cache.Free()

	k := cpu.NewTensor(tensor.Shape{2, 2}, []float32{1, 2, 3, 4})
	v := cpu.NewTensor(tensor.Shape{2, 2}, []float32{5, 6, 7, 8})

	views, start, err := cache.Append(0, k, v)
	if err != nil {
		t.Fatalf("Append: %v", err)
	}
	if start != 0 {
		t.Fatalf("expected start 0, got %d", start)
	}
	if cache.SeqLen() != 0 {
		t.Fatalf("expected SeqLen 0 before commit, got %d", cache.SeqLen())
	}
	if len(views) == 0 {
		t.Fatalf("expected non-empty views")
	}
	last := views[len(views)-1]
	if last.Start+last.Length < 2 {
		t.Fatalf("expected views to include appended tokens, got last view start=%d len=%d", last.Start, last.Length)
	}

	committedViews := cache.Views(0)
	if len(committedViews) != 0 {
		t.Fatalf("expected Views() to be empty before commit, got %d", len(committedViews))
	}

	cache.Commit(2)
	if cache.SeqLen() != 2 {
		t.Fatalf("expected SeqLen 2 after commit, got %d", cache.SeqLen())
	}
	committedViews = cache.Views(0)
	if len(committedViews) == 0 {
		t.Fatalf("expected Views() to be non-empty after commit")
	}
	last = committedViews[len(committedViews)-1]
	if last.Start+last.Length < 2 {
		t.Fatalf("expected committed views to include tokens, got last view start=%d len=%d", last.Start, last.Length)
	}
}

func TestPagedKVCacheViewsPackedLayout(t *testing.T) {
	pool, err := NewBlockPool(BlockPoolConfig{
		NumLayers:  1,
		NumKVHeads: 2,
		HeadDim:    2,
		BlockSize:  4,
		NumBlocks:  4,
		Device:     tensor.CPU,
		GPU:        0,
	})
	if err != nil {
		t.Fatalf("NewBlockPool: %v", err)
	}

	cache := NewPagedKVCache(pool, PagedCacheConfig{
		NumLayers:  1,
		NumKVHeads: 2,
		HeadDim:    2,
		BlockSize:  4,
		MaxSeqLen:  16,
		Device:     tensor.CPU,
		GPU:        0,
	}, "req")
	defer cache.Free()

	// token-major layout: [t][kvHead][d]
	// kvDim = 2 * 2 = 4
	k := cpu.NewTensor(tensor.Shape{2, 4}, []float32{
		1, 2, 3, 4,
		5, 6, 7, 8,
	})
	v := cpu.NewTensor(tensor.Shape{2, 4}, []float32{
		10, 20, 30, 40,
		50, 60, 70, 80,
	})

	if _, _, err := cache.Append(0, k, v); err != nil {
		t.Fatalf("Append: %v", err)
	}

	// Should be available pre-commit (uses numWritten).
	if cache.SeqLen() != 0 {
		t.Fatalf("expected SeqLen 0 before commit, got %d", cache.SeqLen())
	}
	pviews := cache.ViewsPacked(0)
	if len(pviews) == 0 {
		t.Fatalf("expected non-empty packed views")
	}
	if len(pviews) != 1 {
		t.Fatalf("expected 1 packed view, got %d", len(pviews))
	}
	pv := pviews[0]
	if pv.Start != 0 || pv.Length != 2 {
		t.Fatalf("unexpected packed view range: start=%d len=%d", pv.Start, pv.Length)
	}
	if pv.BlockSize != 4 || pv.HeadDim != 2 || pv.NumKVHeads != 2 {
		t.Fatalf("unexpected packed view meta: block=%d headDim=%d kvHeads=%d", pv.BlockSize, pv.HeadDim, pv.NumKVHeads)
	}

	blockSize := pv.BlockSize
	headDim := pv.HeadDim
	numKVHeads := pv.NumKVHeads
	kvDim := numKVHeads * headDim
	for ti := 0; ti < pv.Length; ti++ {
		for h := 0; h < numKVHeads; h++ {
			for d := 0; d < headDim; d++ {
				src := k.DataFloat32()[ti*kvDim+h*headDim+d]
				dst := pv.K[h*(blockSize*headDim)+ti*headDim+d]
				if src != dst {
					t.Fatalf("K packed mismatch t=%d h=%d d=%d: src=%v dst=%v", ti, h, d, src, dst)
				}
				srcV := v.DataFloat32()[ti*kvDim+h*headDim+d]
				dstV := pv.V[h*(blockSize*headDim)+ti*headDim+d]
				if srcV != dstV {
					t.Fatalf("V packed mismatch t=%d h=%d d=%d: src=%v dst=%v", ti, h, d, srcV, dstV)
				}
			}
		}
	}
}