# Test spatial network construction
# These tests verify the correctness of buildSpatialNetwork and related functions

test_that("buildSpatialNetwork returns correct dimensions", {
    skip_if_not_installed("RANN")
    
    set.seed(42)
    n <- 50
    coords <- cbind(x = runif(n), y = runif(n))
    rownames(coords) <- paste0("spot_", seq_len(n))

    W <- buildSpatialNetwork(coords, method = "knn", k = 5)

    expect_equal(nrow(W), n)
    expect_equal(ncol(W), n)
    expect_equal(rownames(W), rownames(coords))
    expect_equal(colnames(W), rownames(coords))
})

test_that("KNN network has correct number of neighbors", {
    skip_if_not_installed("RANN")
    
    set.seed(42)
    n <- 30
    k <- 5
    coords <- cbind(x = runif(n), y = runif(n))
    rownames(coords) <- paste0("spot_", seq_len(n))

    W <- buildSpatialNetwork(coords, method = "knn", k = k, binary = TRUE)

    # Each row should have at least k neighbors (may have more due to symmetry)
    row_sums <- rowSums(W)
    expect_true(all(row_sums >= k))
})

test_that("Delaunay network is symmetric", {
    skip_if_not_installed("geometry")

    set.seed(42)
    n <- 30
    coords <- cbind(x = runif(n), y = runif(n))
    rownames(coords) <- paste0("spot_", seq_len(n))

    W <- buildSpatialNetwork(coords, method = "delaunay", binary = TRUE)

    # Network should be symmetric
    expect_equal(W, t(W))
})

test_that("KNN network is symmetric after union", {
    skip_if_not_installed("RANN")

    set.seed(42)
    n <- 30
    coords <- cbind(x = runif(n), y = runif(n))
    rownames(coords) <- paste0("spot_", seq_len(n))

    W <- buildSpatialNetwork(coords, method = "knn", k = 5, binary = TRUE)

    # Network should be symmetric
    expect_equal(W, t(W))
})

test_that("binary network contains only 0 and 1", {
    skip_if_not_installed("RANN")
    
    set.seed(42)
    n <- 30
    coords <- cbind(x = runif(n), y = runif(n))
    rownames(coords) <- paste0("spot_", seq_len(n))

    W <- buildSpatialNetwork(coords, method = "knn", k = 5, binary = TRUE)

    expect_true(all(W %in% c(0, 1)))
})

test_that("diagonal is zero (no self-connections)", {
    skip_if_not_installed("RANN")
    
    set.seed(42)
    n <- 30
    coords <- cbind(x = runif(n), y = runif(n))
    rownames(coords) <- paste0("spot_", seq_len(n))

    W <- buildSpatialNetwork(coords, method = "knn", k = 5)

    # Diagonal should be all zeros (ignore names)
    expect_true(all(diag(W) == 0))
})

test_that("buildSpatialNetwork handles small datasets", {
    skip_if_not_installed("RANN")
    
    # Very small dataset
    coords_small <- cbind(x = c(0, 1, 2), y = c(0, 0, 0))
    rownames(coords_small) <- paste0("spot_", 1:3)

    # Should work with k = 2 (maximum possible)
    W <- buildSpatialNetwork(coords_small, method = "knn", k = 2)
    expect_equal(nrow(W), 3)
})