add cisa/date.go and cisa/date_test.go

2 files changed, 449 insertions, 0 deletions

diff --git a/cisa/date.go b/cisa/date.go
new file mode 100644
index 0000000..b36b73c
--- /dev/null
+++ b/cisa/date.go
@@ -0,0 +1,139 @@
+package cisa
+
+import (
+  "fmt"
+  "regexp"
+  "strconv"
+)
+
+// YYYY-MM-DD
+type Date uint16
+
+// Returns true if the year is a leap year, and false otherwise.
+//
+// Reference:
+// https://www.timeanddate.com/date/leapyear.html
+func isLeapYear(y uint16) bool {
+  // leap year rules:
+  //   1. year is evenly divisible by 4 and is not evenly divisible by 100
+  //   2. year is evenly divisible by 4 and is evenly divisible by 400
+  return (((y % 4) == 0) && ((y % 100) != 0)) || // rule 1
+         (((y % 4) == 0) && ((y % 400) == 0)) // rule 2
+}
+
+// maximum month days
+var maxMonthDays = []uint16 {
+  31, // jan
+  28, // feb (incorrect for leap years!)
+  31, // mar
+  30, // apr
+  31, // may
+  30, // jun
+  31, // jul
+  31, // aug
+  30, // sep
+  31, // oct
+  30, // nov
+  31, // dec
+}
+
+// Get the maximum day for the given year and month.
+func getMaxMonthDay(y, m uint16) uint16 {
+  if m == 2 && isLeapYear(y) {
+    return 29
+  } else {
+    return maxMonthDays[m - 1]
+  }
+}
+
+// Parse date component and check range.
+func parseDateComponent(name string, s []byte, min, max uint16) (uint16, error) {
+  // parse value
+  vr, err := strconv.ParseUint(string(s), 10, 32)
+  if err != nil {
+    return 0, err
+  }
+
+  v := uint16(vr)
+
+  // check range
+  if v < min || v > max {
+    return 0, fmt.Errorf("%s component out of range [%d, %d]: %d", name, v, min, max)
+  }
+
+  return uint16(v), nil
+}
+
+var dateRe = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}$`)
+
+// Create date from byte slice.
+func NewDate(s []byte) (Date, error) {
+  var r Date
+
+  if !dateRe.Match(s) {
+    return r, fmt.Errorf("invalid date: \"%s\"", s)
+  }
+
+  // parse year
+  y, err := parseDateComponent("year", s[0:4], 1999, 2126)
+  if err != nil {
+    return r, err
+  }
+
+  // parse month
+  m, err := parseDateComponent("month", s[5:7], 1, 12)
+  if err != nil {
+    return r, err
+  }
+
+  // parse day
+  d, err := parseDateComponent("month", s[8:10], 1, getMaxMonthDay(y, m))
+  if err != nil {
+    return r, err
+  }
+
+  // encode return date
+  r = Date((((y - 1999) & 0x3f) << 9) |
+           (((m - 1) & 0xf) << 5) |
+           ((d - 1) & 0x1f))
+
+  // return result
+  return r, nil
+}
+
+// Get year, month, and day components.
+func (me Date) GetComponents() (uint16, uint16, uint16) {
+  // extract components
+  y := uint16((uint16(me) >> 9) + 1999)
+  m := uint16(((uint16(me) >> 5) & 0xf) + 1)
+  d := uint16((uint16(me) & 0x1f) + 1)
+
+  return y, m, d
+}
+
+// Get year component.
+func (me Date) Year() uint16 {
+  y, _, _ := me.GetComponents()
+  return y
+}
+
+// Get month component.
+func (me Date) Month() uint16 {
+  _, m, _ := me.GetComponents()
+  return m
+}
+
+// Get day component.
+func (me Date) Day() uint16 {
+  _, _, d := me.GetComponents()
+  return d
+}
+
+// Convert to string.
+func (me Date) String() string {
+  // extract date components
+  y, m, d := me.GetComponents()
+
+  // return string
+  return fmt.Sprintf("%d-%d-%d", y, m, d)
+}
diff --git a/cisa/date_test.go b/cisa/date_test.go
new file mode 100644
index 0000000..c64f618
--- /dev/null
+++ b/cisa/date_test.go
@@ -0,0 +1,310 @@
+package cisa
+
+import (
+  "fmt"
+  "reflect"
+  "testing"
+)
+
+func TestIsLeapYear(t *testing.T) {
+  tests := []struct {
+    val uint16
+    exp bool
+  } {
+    { 1800, false },
+    { 1900, false },
+    { 1996, true },
+    { 1997, false },
+    { 1998, false },
+    { 1999, false },
+    { 2000, true },
+    { 2001, false },
+    { 2002, false },
+    { 2003, false },
+    { 2004, true },
+    { 2005, false },
+    { 2006, false },
+    { 2007, false },
+    { 2008, true },
+    { 2009, false },
+    { 2010, false },
+    { 2011, false },
+    { 2012, true },
+    { 2013, false },
+    { 2014, false },
+    { 2015, false },
+    { 2016, true },
+    { 2017, false },
+    { 2018, false },
+    { 2019, false },
+    { 2020, true },
+    { 2021, false },
+    { 2022, false },
+    { 2023, false },
+    { 2024, true },
+    { 2100, false },
+    { 2400, true },
+  }
+
+  for _, test := range(tests) {
+    t.Run(fmt.Sprintf("%d", test.val), func(t *testing.T) {
+      got := isLeapYear(test.val)
+      if got != test.exp {
+        t.Errorf("got %v, exp %v", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestGetMaxMonthDay(t *testing.T) {
+  tests := []struct {
+    y uint16
+    m uint16
+    exp uint16
+  } {
+    { 2000, 2, 29 }, // test leap year
+    { 2001, 2, 28 }, // test non-leap year
+    { 2022, 1, 31 }, // test full non-leap year
+    { 2022, 2, 28 },
+    { 2022, 3, 31 },
+    { 2022, 4, 30 },
+    { 2022, 5, 31 },
+    { 2022, 6, 30 },
+    { 2022, 7, 31 },
+    { 2022, 8, 31 },
+    { 2022, 9, 30 },
+    { 2022, 10, 31 },
+    { 2022, 11, 30 },
+    { 2022, 12, 31 },
+  }
+
+  for _, test := range(tests) {
+    t.Run(fmt.Sprintf("%04d-%02d", test.y, test.m), func(t *testing.T) {
+      got := getMaxMonthDay(test.y, test.m)
+      if got != test.exp {
+        t.Errorf("got %v, exp %v", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestParseDateComponent(t *testing.T) {
+  tests := []struct {
+    name  string
+    val   string
+    min   uint16
+    max   uint16
+    exp   bool
+  } {
+    { "bad-uint", "abcd", 2000, 2001, false },
+    { "y-pass", "2000", 2000, 2001, true },
+    { "y-fail-lo", "1999", 2000, 2001, false },
+    { "y-fail-hi", "2002", 2000, 2001, false },
+    { "m-pass-1", "1", 1, 12, true },
+    { "m-pass-2", "2", 1, 12, true },
+    { "m-pass-3", "3", 1, 12, true },
+    { "m-pass-4", "4", 1, 12, true },
+    { "m-pass-5", "5", 1, 12, true },
+    { "m-pass-6", "6", 1, 12, true },
+    { "m-pass-7", "7", 1, 12, true },
+    { "m-pass-8", "8", 1, 12, true },
+    { "m-pass-9", "9", 1, 12, true },
+    { "m-pass-10", "10", 1, 12, true },
+    { "m-pass-11", "11", 1, 12, true },
+    { "m-pass-12", "12", 1, 12, true },
+    { "m-fail-lo", "0", 1, 12, false },
+    { "m-fail-hi", "13", 1, 12, false },
+    { "d-pass-1", "1", 1, 31, true },
+    { "d-pass-10", "10", 1, 31, true },
+    { "d-pass-30", "10", 1, 31, true },
+    { "d-fail-lo", "0", 1, 31, false },
+    { "d-fail-hi", "32", 1, 31, false },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.name, func(t *testing.T) {
+      got, err := parseDateComponent("a", []byte(test.val), test.min, test.max)
+      if err != nil && test.exp == true {
+        t.Error(err)
+      } else if err == nil && test.exp == false {
+        t.Errorf("got %v, exp error", got)
+      }
+    })
+  }
+}
+
+func TestNewDate(t *testing.T) {
+  tests := []struct {
+    name string
+    val string
+    exp bool
+  } {
+    { "pass", "2000-01-03", true },
+    { "pass-lo", "1999-01-01", true },
+    { "pass-hi", "2126-12-31", true },
+    { "fail", "asdf", false },
+    { "fail-y-lo", "1998-01-03", false },
+    { "fail-y-hi", "2128-01-03", false },
+    { "fail-m-lo", "2126-00-03", false },
+    { "fail-m-hi", "2126-13-03", false },
+    { "fail-d-lo", "2126-01-00", false },
+    { "fail-d-hi", "2126-01-32", false },
+    { "fail-d-hi", "2126-02-29", false },
+    { "fail-d-hi", "2126-03-32", false },
+    { "fail-d-hi", "2126-04-31", false },
+    { "fail-d-hi", "2126-05-32", false },
+    { "fail-d-hi", "2126-06-31", false },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.name, func(t *testing.T) {
+      if got, err := NewDate([]byte(test.val)); err != nil && test.exp {
+        t.Error(err)
+      } else if err == nil && !test.exp {
+        t.Errorf("got %v, exp error", got)
+      }
+    })
+  }
+}
+
+func TestGetComponents(t *testing.T) {
+  type date struct {
+    y uint16
+    m uint16
+    d uint16
+  }
+
+  tests := []struct {
+    val string
+    exp date
+  } {
+    { "2022-10-31", date { 2022, 10, 31 } },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      // create date
+      dt, err := NewDate([]byte(test.val))
+      if err != nil {
+        t.Error(err)
+        return
+      }
+
+      // get components
+      y, m, d := dt.GetComponents()
+      got := date { y, m, d }
+
+      // check components
+      if !reflect.DeepEqual(got, test.exp) {
+        t.Errorf("got %v, exp %v", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestYear(t *testing.T) {
+  tests := []struct {
+    val string
+    exp uint16
+  } {
+    { "2022-10-31", 2022 },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      // create date
+      dt, err := NewDate([]byte(test.val))
+      if err != nil {
+        t.Error(err)
+        return
+      }
+
+      // get year
+      got := dt.Year()
+
+      // check components
+      if got != test.exp {
+        t.Errorf("got year %d, exp %d", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestMonth(t *testing.T) {
+  tests := []struct {
+    val string
+    exp uint16
+  } {
+    { "2022-10-31", 10 },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      // create date
+      dt, err := NewDate([]byte(test.val))
+      if err != nil {
+        t.Error(err)
+        return
+      }
+
+      // get month
+      got := dt.Month()
+
+      // check components
+      if got != test.exp {
+        t.Errorf("got month %d, exp %d", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestDay(t *testing.T) {
+  tests := []struct {
+    val string
+    exp uint16
+  } {
+    { "2022-10-31", 31 },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      // create date
+      dt, err := NewDate([]byte(test.val))
+      if err != nil {
+        t.Error(err)
+        return
+      }
+
+      // get day
+      got := dt.Day()
+
+      // check components
+      if got != test.exp {
+        t.Errorf("got day %d, exp %d", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestString(t *testing.T) {
+  tests := []string {
+    "2022-10-31",
+  }
+
+  for _, test := range(tests) {
+    t.Run(test, func(t *testing.T) {
+      // create date
+      dt, err := NewDate([]byte(test))
+      if err != nil {
+        t.Error(err)
+        return
+      }
+
+      // get/check string
+      got := dt.String()
+      if got != test {
+        t.Errorf("got %s, exp %s", got, test)
+      }
+    })
+  }
+}