This document contains the coding standards for Gazelle.
This document is a work-in-progress and is subject to change.

NOTE: The standards defined in this document will likely differ from
what is actually seen in the Gazelle code. This document is the first
step in properly enforcing coding standards throughout the project.

== TABLE OF CONTENTS ==

1.    LINTING
2.    FILE FORMATTING
3.    CODE STYLING
3.1        Code styling for PHP and JavaScript
3.2        Code styling for CSS
3.3        Code styling for SQL
4.    NAMING CONVENTIONS
4.1        Function names
4.2        Variable names
4.3        Class names
4.4        SQL names
4.5        Miscellaneous names
5.    COMMENTS
6.    USER INTERFACE
7.    EXAMPLES
7.1        PHP examples
7.2        CSS examples
7.3        SQL examples


# LINTING

To help ensure adherence to this guide, we have setup linting for PHP and SCSS code. They can
be run through make:

make lint-php
make lint-css

These steps are also run on committing.

# FILE FORMATTING

Spaces shall always be used for indentation. 4-space indents are used.

Files shall be encoded in UTF-8.

Files shall always use Unix-style line endings (LF). The program dos2unix
will take care of this for you, if you have files that use Windows-style
line endings (CR+LF) or old Mac-style line endings (CR).

Files must end with a new-line character. Use a proper editor that
performs this automatically.

File names for PHP, CSS, and JavaScript files may not contain spaces.


# CODE STYLING

## Code styling for PHP and JavaScript

All statement blocks, including functions, shall have the opening brace
at the end of the same line with a space before the brace. The astute
reader will note that this is K&R style with the exception of the opening
brace in function definitions.

There shall be a space between a control structure statement (e.g. `if`,
`elseif` in PHP, `for`) and the following parenthesis.

PHP files shall not end with a trailing `?>`.

There shall be a space around conditional operators.

When using ternary operators, spaces shall be used around the operators.

For PHP conditional blocks, `elseif` is to be used instead of `else if`.

In loops and conditional blocks, there shall be braces even if there is
only one statement.

In loops and conditional blocks, the statement(s) shall be placed on
separate lines.

When opening a PHP statement, `<?php` shall be used instead of `<?`. In
other words, short tags are forbidden. When using <?= ... ?> there shall
be spaces at either end of the block (so that it is easy to grab the
contents in vim with e.g. `yE`).

When declaring an array, the short syntax `[]` shall be used, instead
of the longer `array()`.

In general, any syntax as of PHP 7.3 is permitted, and probably
recommended, in the interest of brevity and clarity. Trailing commas
in lists are allowed, and recommended.

Use indents as appropriate to aid readability. When functions with
many parameters are laid out over multiple lines, the subsequent lines
are indented 4 characters (and not to the opening parenthesis above).

    $result = someFunction(
        anotherFunc(1, 2, 3),
        yetAnotherFunc(4, 5 6),
    );

Switch cases in index files shall not contain substantial code. The use
of include statements is acceptable.

When declaring JavaScript variables, `var` shall always be used.

When manually type casting, whitespace should not be used between the
cast operator and the variable.

## Code styling for CSS

`property: value;` pairs shall be separated by a space, and the value
shall be followed by a semi-colon.

Multiple, related CSS selectors with the same declarations shall appear
on multiple lines to improve readability.

The opening brace shall be on the same line as the last related
selector with a space between the selector and the brace.

## Code styling for SQL

Long SQL queries shall be separated on multiple lines.

Short SQL queries may be on a single line.

All SQL keywords shall be uppercase. `count()`, `sum()`, `now()` are not
keywords, they are functions.

All queries that have external inputs shall use placeholders. Queries
with arbitrary numbers of external inputs should use placeholders().

Aliases shall be used to refer to any columns whenever multiple tables are
joined in an SQL query. They shall be using the `tbl_name AS alias_name`
syntax. Table aliases must be used for single-table queries (because one
day a second table will be added to the query). Table aliases can be
constructed from the first letter of each word in the name (`users_main`
becomes `um`).

The primary SQL keywords should be at the same indentation level.
(`SELECT`, `FROM`, 'INNER JOIN`, `WHERE`, `GROUP BY`, `HAVING`, `ORDER BY`).

The SQL keywords `INNER JOIN`, `RIGHT JOIN`, `LEFT JOIN` are at the same
level as the `SELECT` statement. The `JOIN` abbreviation for `INNER JOIN`
is not accepted. `NATURAL JOIN` is forbidden.

Join clauses must be parenthesized: `a INNER JOIN b IN (a.foo = b.kek)`
When the column names match `USING` is preferred `a INNER JOIN b USING (kek)`.

The SQL keyword `AND` must be indented once from the `WHERE` (and similar)
statements.

`UPDATE` that update multiple columns have one column per line. The `SET`
clause is kept on the same line as the `UPDATE` statement, except in the
case of a multi-table update against a derived table, where it sits on a
line by itself.

The "not equal to" operator `!=` must be used instead of the alternative
operator `<>`.

## Naming conventions for new tables

(Legacy tables are exempt).

Names are always singular.

The primary key is named `<table>_id`.

Zero dates are forbidden.

Numeric enums (`'0', '1', '2'`) are forbidden. Use descriptive names.

# NAMING CONVENTIONS

Function, variable, and class names shall always be descriptive.

## Function names

PHP function names shall be written in `camelCase`.

JavaScript function names shall be written in `camelCase` with a leading
lowercase letter.

## Variable names

PHP variable names shall be written in `camelCase`.

JavaScript global-scope variables shall be written in `camelCase` with a
leading lowercase letter.

JavaScript local-scope variables shall be written in
`lowercase_with_underscores`.

## Class names

PHP class names shall be written in `CamelCase` with a leading uppercase
letter.

PHP class constants shall be written in `CamelCase` with a leading
uppercase letter.

PHP global constants shall be written in `ALL_CAPS`.

PHP constants `true`, `false`, and `null` shall be written in all lowercase.

## SQL names

All SQL keywords shall be written in all UPPERCASE.

All SQL table names shall be written in `lowercase_with_underscores`.

All legacy SQL column names are be written in `CamelCase` with a leading
uppercase letter.

All new column names shall be written in `lowercase_with_underscores`.

All automatically-incremented ID columns shall be named `<table>_id`,
while the other columns for ids shall have names like `collage_id`,
`user_id`.  etc.

## Miscellaneous names

# COMMENTS

Use C89-style `/* ... */` comments for multi-line comments.

Use C99-style `// ...` comments for single-line comments.


# USER INTERFACE

All button labels shall use sentence case.

All table headings shall use sentence case.

All text-based buttons shall use the `brackets` CSS class.

Use common sense for design-related code. Microsoft's UI design guidelines
explain when certain form input controls should be used over others to
provide a familiar and intuitive interface. Refer to the following links
for the most likely issues to encounter in web design:

* http://msdn.microsoft.com/en-us/library/windows/desktop/aa511452.aspx
* http://msdn.microsoft.com/en-us/library/windows/desktop/aa511453.aspx
* http://msdn.microsoft.com/en-us/library/windows/desktop/aa511488.aspx
* http://msdn.microsoft.com/en-us/library/windows/desktop/aa511494.aspx


# EXAMPLES

## PHP examples

    if ($foo >= 0) {
        $someString = "this is a string $diffString with more text";
    } elseif ($foo == 0) {
        // other things happen
    } else {
        // more magic
    }

    function worksMagic($foo, $bar) {
        return $foo;
    }

    echo ($foo == true ? 'foo is true' : 'foo is false');

    if ($foo == true) {
        // magic happens
    }

    /*
     * This is a good, multi-line comment.
     *
     * Please comment your code!
     */

    // This is a good, single-line comment.


## CSS examples

    <a href="foobar.php" style="font-weight: bold;">link text</a>

    .spellcheck {
        margin: 10px 0;
        font-size: 1.25em;
        font-weight: bold;
    }

    .linkbox .brackets:before,
    .linkbox .brackets:after,
    .top10_quantity_links .brackets:before,
    .top10_quantity_links .brackets:after {
        color: #757575;
    }


# SQL examples

    SELECT
        r.ID, e.EditionID, r.Title, r.Year, r.CatalogueNumber,
        l.Name AS Label, r.LabelID, r.Image, r.MusicBrainzID
    FROM releases AS r
    INNER JOIN editions AS e ON (e.ReleaseID = r.ID)
    LEFT JOIN labels AS l ON (l.ID = r.LabelID)
    WHERE r.ID IN (?, ?, ?)
    ORDER BY e.EditionID, r.Year ASC

    SELECT c.ID, c.Subject, cu.Unread, cu.Sticky,
        cu.ForwardedTo, cu2.UserID, cu.ReceivedDate AS Date
    FROM pm_conversations AS c
    LEFT JOIN pm_conversations_users AS cu
        ON (cu.ConvID = c.ID AND cu.UserID = '1')
    LEFT JOIN pm_conversations_users AS cu2
        ON (cu2.ConvID = c.ID AND cu2.UserID != '1' AND cu2.ForwardedTo = 0)
    LEFT JOIN users_main AS um ON (um.ID = cu2.UserID)
    WHERE um.Username LIKE 'test'
        AND cu.InInbox = '1'
    GROUP BY c.ID
    ORDER BY cu.Sticky, Date DESC
    LIMIT 25

    SELECT RequestID AS ID, UserID FROM bookmarks_requests br