context("Minimum diameter spanning tree")

lc_collate <- Sys.getlocale("LC_COLLATE")
Sys.setlocale("LC_COLLATE", "C")

# Simple line graph with 5 vertices, 4 edges
test_that("absolute.one.center of a 5-vertex line graph is on the middle vertex", {
  n <- 5
  g <- graph.edgelist(matrix(c(1:(n-1), 2:n), ncol=2))
  expect_that(local.center(g, 1), equals(c('e' = 1, 't' = 1, 'r' = 3)))
  expect_that(local.center(g, 2), equals(c('e' = 2, 't' = 1, 'r' = 2)))
  expect_that(local.center(g, 3), equals(c('e' = 3, 't' = 0, 'r' = 2)))
  expect_that(local.center(g, 4), equals(c('e' = 4, 't' = 0, 'r' = 3)))
  expect_that(absolute.one.center(g), equals(c('e' = 2, 't' = 1, 'r' = 2)))
})

# With edge lengths (weights)
test_that("absolute.one.center takes edge weights into account", {
  n <- 5
  g <- graph.edgelist(matrix(c(1:(n-1), 2:n), ncol=2))
  g <- set.edge.attribute(g, 'weight', value=c(1, 1, 1, 0.5))
  expect_that(local.center(g, 2), equals(c('e' = 2, 't' = 0.75, 'r' = 1.75)))
  expect_that(local.center(g, 3), equals(c('e' = 3, 't' = 0, 'r' = 2)))
  expect_that(absolute.one.center(g), equals(c('e' = 2, 't' = 0.75, 'r' = 1.75)))
})

# Simple line graph with 6 vertices, 5 edges
test_that("absolute.one.center of 6-vertex line graph is on the middle of the middle edge", {
  n <- 6
  g <- graph.edgelist(matrix(c(1:(n-1), 2:n), ncol=2))
  expect_that(local.center(g, 1), equals(c('e' = 1, 't' = 1, 'r' = 4)))
  expect_that(local.center(g, 2), equals(c('e' = 2, 't' = 1, 'r' = 3)))
  expect_that(local.center(g, 3), equals(c('e' = 3, 't' = 0.5, 'r' = 2.5)))
  expect_that(local.center(g, 4), equals(c('e' = 4, 't' = 0, 'r' = 3)))
  expect_that(absolute.one.center(g), equals(c('e' = 3, 't' = 0.5, 'r' = 2.5)))
})

# Slightly less simple graph
test_that("absolute.one.center of a non-line graph is correct", {
  g <- graph.edgelist(rbind(c(1, 2), c(1, 3), c(1, 4), c(4, 5)))
  expect_that(local.center(g, 1), equals(c('e' = 1, 't' = 0, 'r' = 2)))
  expect_that(local.center(g, 2), equals(c('e' = 2, 't' = 0, 'r' = 2)))
  expect_that(local.center(g, 3), equals(c('e' = 3, 't' = 0.5, 'r' = 1.5)))
  expect_that(local.center(g, 4), equals(c('e' = 4, 't' = 0, 'r' = 2)))
  expect_that(absolute.one.center(g), equals(c('e' = 3, 't' = 0.5, 'r' = 1.5)))
})

# Graph with a cycle
test_that("absolute.once.center of a cyclic graph is correct", {
  g <- graph.edgelist(rbind(c(1, 2), c(1, 3), c(1, 4), c(1, 5), c(4, 5)))
  expect_that(local.center(g, 1), equals(c('e' = 1, 't' = 0, 'r' = 1)))
  expect_that(local.center(g, 2), equals(c('e' = 2, 't' = 0, 'r' = 1)))
  expect_that(local.center(g, 3), equals(c('e' = 3, 't' = 0, 'r' = 1)))
  expect_that(local.center(g, 4), equals(c('e' = 4, 't' = 0, 'r' = 1)))
  expect_that(local.center(g, 5), equals(c('e' = 5, 't' = 0, 'r' = 2)))
  expect_that(absolute.one.center(g), equals(c('e' = 1, 't' = 0, 'r' = 1)))
})

# Graph with only one edge
test_that("absolute.once.center of one-edge graph is correct", {
  g <- graph.edgelist(rbind(c(1, 2)))
  expect_that(local.center(g, 1), equals(c('e' = 1, 't' = 0.5, 'r' = 0.5)))
  expect_that(absolute.one.center(g), equals(c('e' = 1, 't' = 0.5, 'r' = 0.5)))
})

# Complex real network (luades-thrombolytic)
test_that("absolute.one.center of complex graph is correct", {
  v <- as.factor(c("ASPAC", "AtPA", "Ret", "SK", "SKtPA", "Ten", "tPA", "UK"))
  e <- list(
    c("ASPAC", "AtPA"),
    c("ASPAC", "tPA"),
    c("ASPAC", "SK"),
    c("AtPA", "Ten"),
    c("AtPA", "SKtPA"),
    c("AtPA", "Ret"),
    c("AtPA", "SK"),
    c("AtPA", "UK"),
    c("Ret", "SK"),
    c("SK", "UK"),
    c("SK", "SKtPA"),
    c("SK", "tPA"),
    c("tPA", "UK")
  )
  e <- do.call(rbind, lapply(e, function(x) { factor(x, levels=levels(v)) }))
  g <- graph.edgelist(e)
  V(g)$name <- levels(v)
  expect_that(absolute.one.center(g), equals(c('e' = 1, 't' = 0.5, 'r' = 1.5)))

  tree <- minimum.diameter.spanning.tree(g)
  expect_that(degree(tree, mode="out"), equals(c(
    'ASPAC'=3, 'AtPA'=4, 'Ret'=0, 'SK'=0, 'SKtPA'=0, 'Ten'=0, 'UK'=0, 'tPA'=0)))
  expect_that(degree(tree, mode="in"), equals(c(
    'ASPAC'=0, 'AtPA'=1, 'Ret'=1, 'SK'=1, 'SKtPA'=1, 'Ten'=1, 'UK'=1, 'tPA'=1)))
  expect_that(tree['AtPA', 'SK'], equals(0))
  expect_that(tree['ASPAC', 'AtPA'], equals(1))
})

Sys.setlocale("LC_COLLATE", lc_collate)