defmodule BibleEx.Librarian do
@moduledoc """
Internal helper functions for looking up Bible metadata and validating references.
This module is used by `BibleEx.Reference` and `BibleEx.RefParser` to:
* Resolve book names into canonical numbers and name variants.
* Compute last chapters and verses for a given book.
* Build lists of `BibleEx.Chapter` and `BibleEx.Verse` structs.
* Infer reference types and validate that references are in range.
* Render human-readable reference strings.
"""
require Logger
alias BibleEx.BibleData
@doc ~S"""
Returns the book number (1–66) for a given book identifier.
The `book` argument may be:
* The full lowercased book name, e.g. `"genesis"`.
* An OSIS identifier, e.g. `"gen"`.
* A shortened/abbreviated key from `BibleEx.BibleData`.
* A variant key, e.g. `"mat"` for Matthew.
If the book cannot be resolved, `nil` is returned.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.find_book_number(book: "Genesis")
1
iex> Librarian.find_book_number(book: "rom")
45
iex> Librarian.find_book_number(book: "NotABook")
nil
"""
def find_book_number(book: book) do
book_lower = String.downcase(book)
cond do
book_lower == "" ->
nil
BibleData.books()[book_lower] ->
BibleData.books()[book_lower]
BibleData.osis_books()[book_lower] ->
BibleData.osis_books()[book_lower]
BibleData.shortened_books()[book_lower] ->
BibleData.shortened_books()[book_lower]
BibleData.variants()[book_lower] ->
BibleData.variants()[book_lower]
true ->
nil
end
end
@doc ~S"""
Returns `true` if the given book string is a recognized Bible book.
This check uses the canonical, OSIS, and shortened maps in `BibleEx.BibleData`
and does not attempt to correct misspellings.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.check_book(book: "Genesis")
true
iex> Librarian.check_book(book: "Gen")
true
iex> Librarian.check_book(book: "NotABook")
false
"""
def check_book(book: book) do
book_lower = String.downcase(book)
Map.has_key?(BibleData.books(), book_lower) ||
Map.has_key?(BibleData.osis_books(), book_lower) ||
Map.has_key?(BibleData.shortened_books(), book_lower)
end
@doc ~S"""
Returns all name variants for a book as a map.
The result map contains:
* `:osis` – OSIS identifier (e.g. `"Gen"`)
* `:abbr` – Paratext-style abbreviation (e.g. `"GEN"`)
* `:name` – Full book name (e.g. `"Genesis"`)
* `:short` – Shortened form (e.g. `"Gn"`)
The `book` argument may be a name/abbreviation string or a 1-based book number.
If the book cannot be resolved, an empty map is returned.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.get_book_names(book: "Genesis")[:name]
"Genesis"
iex> Librarian.get_book_names(book: 45)[:osis]
"Rom"
iex> Librarian.get_book_names(book: "NotABook")
%{}
"""
def get_book_names(book: book) do
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
"nil" -> nil
"atom" -> nil
end
case found_book do
nil ->
%{}
found_book ->
list = Enum.at(BibleData.book_names(), found_book - 1)
%{
osis: Enum.at(list, 0),
abbr: Enum.at(list, 1),
name: Enum.at(list, 2),
short: Enum.at(list, 3)
}
end
end
@doc ~S"""
Returns the last verse number for a given book, or for a specific chapter.
When only `book` is given, the last verse in the final chapter is returned.
When `chapter` is given, the last verse in that chapter is returned, or `nil`
if the chapter is out of range.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.get_last_verse_number(book: "Genesis", chapter: 1) > 0
true
iex> Librarian.get_last_verse_number(book: "Revelation")
v when is_integer(v) and v > 0
iex> Librarian.get_last_verse_number(book: "Genesis", chapter: 999)
nil
"""
def get_last_verse_number(book: book) do
get_last_verse_number(book: book, chapter: nil)
end
def get_last_verse_number(book: book, chapter: chapter) do
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
case found_book do
nil ->
nil
_found_book_not_nil ->
found_chapter =
case chapter do
nil -> length(Enum.at(BibleData.last_verse(), found_book - 1))
found -> found
end
if length(Enum.at(BibleData.last_verse(), found_book - 1)) < found_chapter ||
found_chapter < 1 do
nil
else
verses_in_book = Enum.at(BibleData.last_verse(), found_book - 1)
Enum.at(verses_in_book, found_chapter - 1)
end
end
end
@doc ~S"""
Returns the number of chapters in a book.
The `book` argument may be a name/abbreviation string or a book number.
If the book is not recognized, `nil` is returned.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.get_last_chapter_number(book: "Genesis")
50
iex> Librarian.get_last_chapter_number(book: "NotABook")
nil
"""
def get_last_chapter_number(book: book) do
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
if found_book > BibleData.last_verse() do
nil
else
length(Enum.at(BibleData.last_verse(), found_book - 1))
end
end
@doc ~S"""
Builds a `BibleEx.Verse` struct for the last verse of a book or chapter.
When only `book` is given, the verse is the last verse of the last chapter.
When `chapter` is given, the verse is the last verse of that chapter.
Returns `nil` if the book or chapter cannot be resolved.
## Examples
iex> alias BibleEx.Librarian
iex> last = Librarian.get_last_verse(book: "Jude")
iex> {last.chapter_number, last.verse_number}
{1, v} when v > 0
iex> Librarian.get_last_verse(book: "NotABook")
nil
"""
def get_last_verse(book: book) do
get_last_verse(book: book, chapter: nil)
end
def get_last_verse(book: book, chapter: chapter) do
book_number =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
book_chapter =
case chapter do
nil -> length(Enum.at(BibleData.last_verse(), book_number - 1))
chapter -> chapter
end
book_names = get_book_names(book: book)
if is_nil(book_number) do
nil
else
case Map.get(book_names, :name, nil) do
nil ->
nil
book_name ->
BibleEx.Verse.new(
book: book_name,
chapter_number: book_chapter,
verse_number: get_last_verse_number(book: book_number, chapter: book_chapter)
)
end
end
end
@doc ~S"""
Returns all verses in a chapter as a list of `BibleEx.Verse` structs.
When only `book` and `chapter` are given, the entire chapter is returned.
When `start_verse` and/or `end_verse` are given, a subrange of verses is returned.
Returns `nil` if the book or chapter is invalid, or if the requested range
is out of bounds (e.g. `start_verse > end_verse`).
## Examples
iex> alias BibleEx.Librarian
iex> verses = Librarian.get_verses(book: "Genesis", chapter: 1)
iex> hd(verses).reference
"Genesis 1:1"
iex> range = Librarian.get_verses(book: "Genesis", chapter: 1, start_verse: 1, end_verse: 3)
iex> Enum.map(range, & &1.verse_number)
[1, 2, 3]
"""
def get_verses(book: book, chapter: chapter) do
get_verses(book: book, chapter: chapter, start_verse: nil, end_verse: nil)
end
def get_verses(book: book, chapter: chapter, start_verse: start_verse, end_verse: end_verse) do
book_number =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
if is_nil(book_number) do
nil
else
case chapter do
nil ->
nil
chapter ->
start_verse =
if !is_nil(start_verse), do: start_verse, else: 1
end_verse =
if !is_nil(end_verse) do
end_verse
else
BibleData.last_verse()
|> Enum.at(book_number - 1)
|> Enum.at(chapter - 1)
end
case start_verse > end_verse do
true ->
nil
false ->
case end_verse do
nil ->
nil
last_verse ->
book_names = get_book_names(book: book)
case Map.get(book_names, :name, nil) do
nil ->
nil
book_name ->
Enum.map(start_verse..last_verse, fn x ->
BibleEx.Verse.new(
book: book_name,
chapter_number: chapter,
verse_number: x
)
end)
end
end
end
end
end
end
@doc ~S"""
Returns a `BibleEx.Chapter` for the last chapter of a book.
Returns `nil` if the book cannot be resolved.
## Examples
iex> alias BibleEx.Librarian
iex> ch = Librarian.get_last_chapter(book: "Psalms")
iex> ch.chapter_number
150
"""
def get_last_chapter(book: book) do
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
if found_book > BibleData.last_verse() do
nil
else
book_names = get_book_names(book: book)
case Map.get(book_names, :name, nil) do
nil ->
nil
book_name ->
last_chapter = length(Enum.at(BibleData.last_verse(), found_book - 1))
BibleEx.Chapter.new(book: book_name, chapter_number: last_chapter)
end
end
end
@doc ~S"""
Returns a list of `BibleEx.Chapter` structs for a book.
Supported forms:
* `get_chapters/1` – all chapters in a book.
* `get_chapters/2` – a single chapter.
* `get_chapters/3` – a range of chapters.
Chapters outside the valid range are clamped to the book's first/last chapter.
Returns `nil` if the book is invalid.
## Examples
iex> alias BibleEx.Librarian
iex> chs = Librarian.get_chapters(book: "Genesis")
iex> length(chs)
50
iex> [ch] = Librarian.get_chapters(book: "Genesis", start_chapter: 1)
iex> ch.chapter_number
1
iex> range = Librarian.get_chapters(book: "Genesis", start_chapter: 1, end_chapter: 3)
iex> Enum.map(range, & &1.chapter_number)
[1, 2, 3]
"""
def get_chapters(book: book) do
get_chapters(book: book, start_chapter: nil, end_chapter: nil)
end
def get_chapters(book: book, start_chapter: start_chapter) do
get_chapters(book: book, start_chapter: start_chapter, end_chapter: nil)
end
def get_chapters(book: book, start_chapter: start_chapter, end_chapter: end_chapter) do
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
if found_book > BibleData.last_verse() do
nil
else
book_names = get_book_names(book: book)
if is_nil(found_book) do
nil
else
case Map.get(book_names, :name, nil) do
nil ->
nil
book_name ->
case start_chapter > end_chapter do
true ->
nil
false ->
start_chapter =
if is_nil(start_chapter), do: 1, else: start_chapter
end_chapter =
if is_nil(end_chapter), do: start_chapter, else: end_chapter
start_chapter =
if start_chapter < 1, do: 1, else: start_chapter
end_chapter =
if end_chapter > length(Enum.at(BibleData.last_verse(), found_book - 1)) do
length(Enum.at(BibleData.last_verse(), found_book - 1))
else
end_chapter
end
Enum.map(start_chapter..end_chapter, fn x ->
BibleEx.Chapter.new(book: book_name, chapter_number: x)
end)
end
end
end
end
end
@doc ~S"""
Infers the type of a reference (`:book`, `:chapter`, `:verse`, `:chapter_range`, `:verse_range`).
This set of overloads allows calling with increasing specificity:
* `identify_reference_type/1` – book only.
* `identify_reference_type/2` – book and start chapter.
* `identify_reference_type/3` – book, start chapter, start verse.
* `identify_reference_type/4` – plus end chapter.
* `identify_reference_type/5` – plus end verse.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.identify_reference_type(book: "Genesis")
:book
iex> Librarian.identify_reference_type(book: "Genesis", start_chapter: 1)
:chapter
iex> Librarian.identify_reference_type(book: "Genesis", start_chapter: 1, start_verse: 1)
:verse
iex> Librarian.identify_reference_type(book: "Genesis", start_chapter: 1, end_chapter: 2)
:chapter_range
iex> Librarian.identify_reference_type(book: "Genesis", start_chapter: 1, start_verse: 1, end_chapter: 1, end_verse: 5)
:verse_range
"""
def identify_reference_type(book: book) do
identify_reference_type(
book: book,
start_chapter: nil,
start_verse: nil,
end_chapter: nil,
end_verse: nil
)
end
def identify_reference_type(
book: book,
start_chapter: start_chapter
) do
identify_reference_type(
book: book,
start_chapter: start_chapter,
start_verse: nil,
end_chapter: nil,
end_verse: nil
)
end
def identify_reference_type(
book: book,
start_chapter: start_chapter,
start_verse: start_verse
) do
identify_reference_type(
book: book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: nil,
end_verse: nil
)
end
def identify_reference_type(
book: book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: end_chapter
) do
identify_reference_type(
book: book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: end_chapter,
end_verse: nil
)
end
def identify_reference_type(
book: _book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: end_chapter,
end_verse: end_verse
) do
cond do
is_nil(start_chapter) and is_nil(end_chapter) ->
if !is_nil(start_verse) do
if !is_nil(end_verse) do
:verse_range
else
:verse
end
else
:book
end
!is_nil(start_chapter) and !is_nil(end_chapter) and start_chapter != end_chapter ->
:chapter_range
!is_nil(start_chapter) and (is_nil(end_chapter) or end_chapter == start_chapter) ->
if !is_nil(start_verse) do
if !is_nil(end_verse) do
:verse_range
else
:verse
end
else
:chapter
end
!is_nil(start_verse) and !is_nil(end_verse) ->
:verse_range
!is_nil(start_verse) ->
:verse
true ->
nil
end
end
@doc ~S"""
Validates that a book identifier refers to a real Bible book.
The `book` argument may be a name/abbreviation string or a numeric book
index. Only the book is checked; chapters and verses are not considered
in this arity.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.verify_reference(book: "Genesis")
true
iex> Librarian.verify_reference(book: "NotABook")
false
"""
def verify_reference(book: book) when not is_nil(book) do
verified = true
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
verified =
if !(found_book > 0 and length(BibleEx.BibleData.last_verse()) >= found_book) do
false
else
verified
end
verified
end
@doc ~S"""
Validates a reference consisting of a book and an optional starting chapter.
Checks that:
* The book exists.
* The `start_chapter`, if present, is within the book's chapter range.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 1)
true
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 999)
false
"""
def verify_reference(book: book, start_chapter: start_chapter) when not is_nil(book) do
verified = true
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
verified =
if !(found_book > 0 and length(BibleEx.BibleData.last_verse()) >= found_book) do
false
else
verified
end
# if book is not verified at this point, short-circuit
verified =
case verified do
true ->
if !is_nil(start_chapter) do
books_last_verse = length(BibleEx.BibleData.last_verse() |> Enum.at(found_book - 1))
if !(start_chapter > 0 and books_last_verse >= start_chapter) do
false
else
verified
end
else
verified
end
false ->
false
end
verified
end
@doc ~S"""
Validates a reference with book, starting chapter, and starting verse.
Checks that:
* The book exists.
* The starting chapter exists for that book.
* The starting verse exists within that chapter.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 1, start_verse: 1)
true
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 1, start_verse: 999)
false
"""
def verify_reference(book: book, start_chapter: start_chapter, start_verse: start_verse)
when not is_nil(book) do
verified = true
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
verified =
if !(found_book > 0 and length(BibleEx.BibleData.last_verse()) >= found_book) do
false
else
verified
end
# if book is not verified at this point, short-circuit
verified =
case verified do
true ->
if !is_nil(start_chapter) do
books_last_verse = length(BibleEx.BibleData.last_verse() |> Enum.at(found_book - 1))
if !(start_chapter > 0 and books_last_verse >= start_chapter) do
false
else
verified
end
else
verified
end
false ->
false
end
# check verse range within the chapter
verified =
if is_nil(found_book) do
false
else
case !is_nil(start_verse) do
true ->
if !is_nil(start_chapter) do
books_last_verse_books_start_chapter =
BibleEx.BibleData.last_verse()
|> Enum.at(found_book - 1)
|> Enum.at(start_chapter - 1)
if !(start_verse > 0 and
books_last_verse_books_start_chapter >= start_verse) do
false
else
verified
end
else
false
end
false ->
verified
end
end
verified
end
@doc ~S"""
Validates a reference with book, starting chapter, and ending verse.
This form is used when a verse range is specified in a single chapter
but only the `end_verse` is provided alongside the chapter.
Checks that:
* The book exists.
* The chapter exists.
* The ending verse is within the chapter's verse range.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 1, end_verse: 3)
true
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 1, end_verse: 999)
false
"""
def verify_reference(book: book, start_chapter: start_chapter, end_verse: end_verse)
when not is_nil(book) do
verified = true
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
verified =
if !(found_book > 0 and length(BibleEx.BibleData.last_verse()) >= found_book) do
false
else
verified
end
# if book is not verified at this point, short-circuit
verified =
case verified do
true ->
if !is_nil(start_chapter) do
books_last_verse = length(BibleEx.BibleData.last_verse() |> Enum.at(found_book - 1))
if !(start_chapter > 0 and books_last_verse >= start_chapter) do
false
else
verified
end
else
verified
end
false ->
false
end
verified =
case !is_nil(end_verse) do
true ->
very_last_verse =
BibleEx.BibleData.last_verse()
|> Enum.at(found_book - 1)
|> Enum.at(start_chapter - 1)
if end_verse <= 0 or very_last_verse < end_verse do
false
else
verified
end
false ->
verified
end
verified
end
@doc ~S"""
Validates a fully-specified reference, including optional start and end chapters and verses.
This is the most general form and checks that:
* The book exists.
* The start and end chapters are within range and ordered correctly.
* The start and end verses, if present, are within their chapter ranges and
ordered correctly relative to each other and the chapter range.
It returns `true` for structurally valid references and `false` otherwise;
it does not check theological or translation-specific constraints.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.verify_reference(book: "John", start_chapter: 3, start_verse: 16, end_chapter: 4, end_verse: 3)
true
iex> Librarian.verify_reference(book: "Genesis", start_chapter: 50, start_verse: 1, end_chapter: 49, end_verse: 10)
false
"""
def verify_reference(
book: book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: end_chapter,
end_verse: end_verse
)
when not is_nil(book) do
verified = true
found_book =
case BibleEx.typeof(book) do
"binary" -> find_book_number(book: book)
"number" -> book
end
verified =
if !(found_book < 1 or (found_book > 0 and length(BibleEx.BibleData.last_verse()) >= found_book)) do
false
else
verified
end
verified =
if is_nil(found_book) do
false
else
if !is_nil(start_chapter) do
books_last_verse = length(BibleEx.BibleData.last_verse() |> Enum.at(found_book - 1))
if !(start_chapter > 0 and books_last_verse >= start_chapter) do
false
else
verified
end
if !is_nil(end_chapter) and start_chapter > end_chapter do
false
else
verified
end
else
if !is_nil(end_chapter) or !is_nil(end_verse) do
false
else
verified
end
end
verified =
case !is_nil(start_verse) do
true ->
books_last_verse_books_start_chapter =
BibleEx.BibleData.last_verse()
|> Enum.at(found_book - 1)
|> Enum.at(start_chapter - 1)
if !(start_verse > 0 and books_last_verse_books_start_chapter >= start_verse) do
false
else
verified
end
if !is_nil(end_verse) and !is_nil(start_verse) do
if start_verse > end_verse do
false
else
verified
end
else
verified
end
false ->
verified
end
verified =
case !is_nil(end_chapter) do
true ->
books_last_verse = length(BibleEx.BibleData.last_verse() |> Enum.at(found_book - 1))
if !(books_last_verse >= end_chapter) do
false
else
verified
end
false ->
verified
end
verified =
case !is_nil(end_verse) do
true ->
if is_nil(end_chapter) do
false
else
very_last_verse =
BibleEx.BibleData.last_verse()
|> Enum.at(found_book - 1)
|> Enum.at(end_chapter - 1)
if end_verse > 0 and very_last_verse >= end_verse do
verified
else
if end_verse < start_verse do
false
else
verified
end
end
end
false ->
verified
end
verified
end
verified
end
@doc ~S"""
Renders a human-readable reference string from its components.
This family of functions builds strings such as:
* `"Genesis 1"`
* `"Genesis 1:1"`
* `"John 3:16 - 4:3"`
* `"Genesis 1-2"`
Depending on which arguments are provided, the output adjusts to match
a conventional Bible reference format. If the inputs are not sufficient
to build a reference (for example, missing book and chapter), `nil` is returned.
## Examples
iex> alias BibleEx.Librarian
iex> Librarian.create_reference_string(book: "Genesis", start_chapter: 1)
"Genesis 1"
iex> Librarian.create_reference_string(book: "Genesis", start_chapter: 1, start_verse: 1)
"Genesis 1:1"
iex> Librarian.create_reference_string(book: "John", start_chapter: 3, start_verse: 16, end_chapter: 4, end_verse: 3)
"John 3:16 - 4:3"
"""
def create_reference_string(book: _book) do
nil
end
def create_reference_string(book: book, start_chapter: start_chapter) do
reference = ""
reference =
case !is_nil(book) and !is_nil(start_chapter) do
true -> reference <> book <> " #{start_chapter}"
false -> reference
end
if(reference == "", do: nil, else: reference)
end
def create_reference_string(book: book, start_chapter: start_chapter, start_verse: start_verse) do
reference = ""
reference =
case !is_nil(book) and !is_nil(start_chapter) do
true ->
reference = reference <> book <> " #{start_chapter}"
case !is_nil(start_verse) do
true -> reference <> ":#{start_verse}"
false -> reference
end
false ->
reference
end
if(reference == "", do: nil, else: reference)
end
def create_reference_string(
book: book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: end_chapter
) do
reference = ""
reference =
case !is_nil(book) and !is_nil(start_chapter) do
true ->
reference = reference <> book <> " #{start_chapter}"
if !is_nil(start_verse) and !is_nil(end_chapter) and end_chapter != start_chapter do
reference = reference <> ":#{start_verse}"
reference = reference <> " - #{end_chapter}"
end_chapter_last_verse = get_last_verse_number(book: book, chapter: end_chapter)
if !is_nil(end_chapter_last_verse) do
reference = reference <> ":#{end_chapter_last_verse}"
reference
else
reference
end
else
reference =
if !is_nil(end_chapter) and end_chapter != start_chapter do
reference = reference <> "-#{end_chapter}"
reference
else
reference
end
reference
end
false ->
reference
end
if(reference == "", do: nil, else: reference)
end
def create_reference_string(
book: book,
start_chapter: start_chapter,
start_verse: start_verse,
end_chapter: end_chapter,
end_verse: end_verse
) do
reference = ""
reference =
case !is_nil(book) and !is_nil(start_chapter) do
true ->
reference = reference <> book <> " #{start_chapter}"
if !is_nil(start_verse) and !is_nil(end_chapter) and end_chapter != start_chapter do
reference = reference <> ":#{start_verse}"
reference = reference <> " - #{end_chapter}"
if !is_nil(end_verse) do
reference = reference <> ":#{end_verse}"
reference
else
end_chapter_last_verse = get_last_verse_number(book: book, chapter: end_chapter)
if !is_nil(end_chapter_last_verse) do
reference = reference <> ":#{end_chapter_last_verse}"
reference
else
reference
end
end
else
reference =
if !is_nil(end_verse) and is_nil(start_verse) do
reference = reference <> ":1"
reference
else
if !is_nil(start_verse) do
reference = reference <> ":#{start_verse}"
reference
else
reference
end
end
reference =
if !is_nil(end_chapter) do
reference =
if is_nil(start_verse) and is_nil(end_verse) do
reference =
if start_chapter != end_chapter do
reference <> "-#{end_chapter}"
else
reference
end
reference
else
if start_chapter != end_chapter do
reference <> " - #{end_chapter}"
else
reference
end
reference
end
reference
else
reference
end
reference =
if !is_nil(end_verse) do
reference =
if !is_nil(start_verse) do
reference <> "-#{end_verse}"
else
if !is_nil(end_chapter) do
reference <> " - #{end_chapter}:#{end_verse}"
else
reference <> ":#{end_verse}"
end
end
reference
else
reference
end
reference
end
false ->
reference =
if is_nil(start_chapter) and is_nil(start_verse) do
book
else
reference
end
reference
end
if(reference == "", do: nil, else: reference)
end
end
