package summer.phrasebook

class PluralRulesSpec extends munit.FunSuite:

  // --- getPluralIndex tests ---

  test("English: 2 forms (singular/plural)") {
    assertEquals(PluralRules.getPluralIndex("en", 0), 1)
    assertEquals(PluralRules.getPluralIndex("en", 1), 0)
    assertEquals(PluralRules.getPluralIndex("en", 2), 1)
    assertEquals(PluralRules.getPluralIndex("en", 100), 1)
  }

  test("French: 0 and 1 are singular") {
    assertEquals(PluralRules.getPluralIndex("fr", 0), 0)
    assertEquals(PluralRules.getPluralIndex("fr", 1), 0)
    assertEquals(PluralRules.getPluralIndex("fr", 2), 1)
    assertEquals(PluralRules.getPluralIndex("fr", 5), 1)
  }

  test("Polish: 3 forms (one/few/many)") {
    assertEquals(PluralRules.getPluralIndex("pl", 1), 0)   // one
    assertEquals(PluralRules.getPluralIndex("pl", 2), 1)   // few
    assertEquals(PluralRules.getPluralIndex("pl", 3), 1)   // few
    assertEquals(PluralRules.getPluralIndex("pl", 4), 1)   // few
    assertEquals(PluralRules.getPluralIndex("pl", 5), 2)   // many
    assertEquals(PluralRules.getPluralIndex("pl", 10), 2)  // many
    assertEquals(PluralRules.getPluralIndex("pl", 11), 2)  // many
    assertEquals(PluralRules.getPluralIndex("pl", 12), 2)  // many (12-14 are exceptions)
    assertEquals(PluralRules.getPluralIndex("pl", 13), 2)  // many
    assertEquals(PluralRules.getPluralIndex("pl", 14), 2)  // many
    assertEquals(PluralRules.getPluralIndex("pl", 22), 1)  // few
    assertEquals(PluralRules.getPluralIndex("pl", 23), 1)  // few
    assertEquals(PluralRules.getPluralIndex("pl", 24), 1)  // few
    assertEquals(PluralRules.getPluralIndex("pl", 25), 2)  // many
    assertEquals(PluralRules.getPluralIndex("pl", 100), 2) // many
    assertEquals(PluralRules.getPluralIndex("pl", 112), 2) // many (n%100=12, exception)
  }

  test("Russian: 3 forms (Slavic rule)") {
    assertEquals(PluralRules.getPluralIndex("ru", 1), 0)   // one
    assertEquals(PluralRules.getPluralIndex("ru", 2), 1)   // few
    assertEquals(PluralRules.getPluralIndex("ru", 5), 2)   // many
    assertEquals(PluralRules.getPluralIndex("ru", 11), 2)  // many (exception: 11-19)
    assertEquals(PluralRules.getPluralIndex("ru", 21), 0)  // one
    assertEquals(PluralRules.getPluralIndex("ru", 22), 1)  // few
    assertEquals(PluralRules.getPluralIndex("ru", 25), 2)  // many
    assertEquals(PluralRules.getPluralIndex("ru", 111), 2) // many (n%100=11)
    assertEquals(PluralRules.getPluralIndex("ru", 121), 0) // one (n%10=1, n%100=21)
  }

  test("Czech: 3 forms") {
    assertEquals(PluralRules.getPluralIndex("cs", 1), 0)
    assertEquals(PluralRules.getPluralIndex("cs", 2), 1)
    assertEquals(PluralRules.getPluralIndex("cs", 4), 1)
    assertEquals(PluralRules.getPluralIndex("cs", 5), 2)
    assertEquals(PluralRules.getPluralIndex("cs", 100), 2)
  }

  test("Japanese: no plural (always 0)") {
    assertEquals(PluralRules.getPluralIndex("ja", 0), 0)
    assertEquals(PluralRules.getPluralIndex("ja", 1), 0)
    assertEquals(PluralRules.getPluralIndex("ja", 100), 0)
  }

  test("Chinese: no plural (always 0)") {
    assertEquals(PluralRules.getPluralIndex("zh", 0), 0)
    assertEquals(PluralRules.getPluralIndex("zh", 1), 0)
    assertEquals(PluralRules.getPluralIndex("zh", 42), 0)
  }

  test("Arabic: 6 forms") {
    assertEquals(PluralRules.getPluralIndex("ar", 0), 0)    // zero
    assertEquals(PluralRules.getPluralIndex("ar", 1), 1)    // one
    assertEquals(PluralRules.getPluralIndex("ar", 2), 2)    // two
    assertEquals(PluralRules.getPluralIndex("ar", 3), 3)    // few (3-10)
    assertEquals(PluralRules.getPluralIndex("ar", 10), 3)   // few
    assertEquals(PluralRules.getPluralIndex("ar", 11), 4)   // many (11-99)
    assertEquals(PluralRules.getPluralIndex("ar", 99), 4)   // many
    assertEquals(PluralRules.getPluralIndex("ar", 100), 5)  // other (100+)
    assertEquals(PluralRules.getPluralIndex("ar", 1000), 5) // other
  }

  test("Slovenian: 4 forms") {
    assertEquals(PluralRules.getPluralIndex("sl", 1), 0)   // n%100==1
    assertEquals(PluralRules.getPluralIndex("sl", 2), 1)   // n%100==2
    assertEquals(PluralRules.getPluralIndex("sl", 3), 2)   // n%100==3 or 4
    assertEquals(PluralRules.getPluralIndex("sl", 4), 2)
    assertEquals(PluralRules.getPluralIndex("sl", 5), 3)   // other
    assertEquals(PluralRules.getPluralIndex("sl", 101), 0) // n%100==1
    assertEquals(PluralRules.getPluralIndex("sl", 102), 1) // n%100==2
  }

  test("Welsh: 4 forms") {
    assertEquals(PluralRules.getPluralIndex("cy", 1), 0)
    assertEquals(PluralRules.getPluralIndex("cy", 2), 1)
    assertEquals(PluralRules.getPluralIndex("cy", 8), 2)
    assertEquals(PluralRules.getPluralIndex("cy", 11), 2)
    assertEquals(PluralRules.getPluralIndex("cy", 5), 3)
  }

  test("Maltese: 4 forms") {
    assertEquals(PluralRules.getPluralIndex("mt", 1), 0)   // one
    assertEquals(PluralRules.getPluralIndex("mt", 0), 1)   // few (0, or n%100 2-10)
    assertEquals(PluralRules.getPluralIndex("mt", 2), 1)   // few
    assertEquals(PluralRules.getPluralIndex("mt", 10), 1)  // few
    assertEquals(PluralRules.getPluralIndex("mt", 11), 2)  // many (n%100 11-19)
    assertEquals(PluralRules.getPluralIndex("mt", 19), 2)  // many
    assertEquals(PluralRules.getPluralIndex("mt", 20), 3)  // other
  }

  test("Lithuanian: 3 forms") {
    assertEquals(PluralRules.getPluralIndex("lt", 1), 0)   // one (n%10==1, not 11)
    assertEquals(PluralRules.getPluralIndex("lt", 2), 1)   // few (n%10>=2, n%100<10 or >=20)
    assertEquals(PluralRules.getPluralIndex("lt", 10), 2)  // other
    assertEquals(PluralRules.getPluralIndex("lt", 11), 2)  // exception
    assertEquals(PluralRules.getPluralIndex("lt", 21), 0)  // one
    assertEquals(PluralRules.getPluralIndex("lt", 12), 2)  // exception (n%100 in 10-19)
  }

  test("Latvian: 3 forms") {
    assertEquals(PluralRules.getPluralIndex("lv", 0), 0)   // zero
    assertEquals(PluralRules.getPluralIndex("lv", 1), 1)   // one (n%10==1, not 11)
    assertEquals(PluralRules.getPluralIndex("lv", 2), 2)   // other
    assertEquals(PluralRules.getPluralIndex("lv", 11), 2)  // other (exception)
    assertEquals(PluralRules.getPluralIndex("lv", 21), 1)  // one
  }

  test("Romanian: 3 forms") {
    assertEquals(PluralRules.getPluralIndex("ro", 1), 0)   // one
    assertEquals(PluralRules.getPluralIndex("ro", 0), 1)   // few (0 or n%100 1-19)
    assertEquals(PluralRules.getPluralIndex("ro", 19), 1)  // few
    assertEquals(PluralRules.getPluralIndex("ro", 20), 2)  // other
    assertEquals(PluralRules.getPluralIndex("ro", 100), 2) // other
  }

  test("Macedonian: last digit rule") {
    assertEquals(PluralRules.getPluralIndex("mk", 1), 0)   // n%10==1
    assertEquals(PluralRules.getPluralIndex("mk", 2), 1)
    assertEquals(PluralRules.getPluralIndex("mk", 11), 0)  // n%10==1
    assertEquals(PluralRules.getPluralIndex("mk", 21), 0)  // n%10==1
  }

  test("Irish: 3 forms") {
    assertEquals(PluralRules.getPluralIndex("ga", 1), 0)
    assertEquals(PluralRules.getPluralIndex("ga", 2), 1)
    assertEquals(PluralRules.getPluralIndex("ga", 3), 2)
  }

  test("locale with region uses language portion") {
    // pt_BR should use "pt" rules (2 forms)
    assertEquals(PluralRules.getPluralIndex("pt_BR", 1), 0)
    assertEquals(PluralRules.getPluralIndex("pt_BR", 2), 1)
  }

  test("unknown locale returns 0") {
    assertEquals(PluralRules.getPluralIndex("xx", 5), 0)
  }

  test("negative numbers use absolute value") {
    assertEquals(PluralRules.getPluralIndex("en", -1), 0)
    assertEquals(PluralRules.getPluralIndex("en", -5), 1)
  }

  // --- choose() tests ---

  test("choose with simple English plural") {
    val en = LocaleTag("en")
    assertEquals(PluralRules.choose("item|items", 1, en), "item")
    assertEquals(PluralRules.choose("item|items", 0, en), "items")
    assertEquals(PluralRules.choose("item|items", 5, en), "items")
  }

  test("choose with explicit conditions") {
    val en = LocaleTag("en")
    assertEquals(PluralRules.choose("{0} No items|{1} One item|[2,*] Many items", 0, en), "No items")
    assertEquals(PluralRules.choose("{0} No items|{1} One item|[2,*] Many items", 1, en), "One item")
    assertEquals(PluralRules.choose("{0} No items|{1} One item|[2,*] Many items", 5, en), "Many items")
    assertEquals(PluralRules.choose("{0} No items|{1} One item|[2,*] Many items", 100, en), "Many items")
  }

  test("choose with explicit range") {
    val en = LocaleTag("en")
    assertEquals(PluralRules.choose("[1,3] Few|[4,*] Many", 2, en), "Few")
    assertEquals(PluralRules.choose("[1,3] Few|[4,*] Many", 4, en), "Many")
  }

  test("choose with Polish 3 forms") {
    val pl = LocaleTag("pl")
    val line = "wpis|wpisy|wpisów"
    assertEquals(PluralRules.choose(line, 1, pl), "wpis")
    assertEquals(PluralRules.choose(line, 2, pl), "wpisy")
    assertEquals(PluralRules.choose(line, 5, pl), "wpisów")
    assertEquals(PluralRules.choose(line, 22, pl), "wpisy")
    assertEquals(PluralRules.choose(line, 12, pl), "wpisów")
  }

  test("choose with Arabic 6 forms") {
    val ar = LocaleTag("ar")
    val line = "zero|one|two|few|many|other"
    assertEquals(PluralRules.choose(line, 0, ar), "zero")
    assertEquals(PluralRules.choose(line, 1, ar), "one")
    assertEquals(PluralRules.choose(line, 2, ar), "two")
    assertEquals(PluralRules.choose(line, 5, ar), "few")
    assertEquals(PluralRules.choose(line, 50, ar), "many")
    assertEquals(PluralRules.choose(line, 100, ar), "other")
  }

  test("choose falls back to last segment if index out of bounds") {
    val en = LocaleTag("en")
    // Only 1 segment but English wants index 1 for n!=1
    assertEquals(PluralRules.choose("only one form", 5, en), "only one form")
  }