Refactor: options module

1 files changed, 231 insertions, 0 deletions

diff --git a/src/options/rewrite.rs b/src/options/rewrite.rs
new file mode 100644
index 00000000..076298f7
--- /dev/null
+++ b/src/options/rewrite.rs
@@ -0,0 +1,231 @@
+/// This module applies rewrite rules to the command line options, in order to
+/// 1. Express deprecated usages in the new non-deprecated form
+/// 2. Implement options such as --raw which are defined to be equivalent to some set of
+///    other options.
+use std::process;
+
+use structopt::clap;
+
+use crate::cli;
+use crate::config::user_supplied_option;
+
+pub fn apply_rewrite_rules(opt: &mut cli::Opt, arg_matches: &clap::ArgMatches) {
+    rewrite_style_strings_to_honor_deprecated_minus_plus_options(opt);
+    rewrite_options_to_implement_deprecated_commit_and_file_style_box_option(opt);
+    rewrite_options_to_implement_deprecated_hunk_style_option(opt);
+    rewrite_options_to_implement_deprecated_theme_option(opt, arg_matches);
+}
+
+/// Honor deprecated --theme
+fn rewrite_options_to_implement_deprecated_theme_option(
+    opt: &mut cli::Opt,
+    arg_matches: &clap::ArgMatches,
+) {
+    if user_supplied_option("deprecated-theme", arg_matches) {
+        if let Some(syntax_theme) = opt.deprecated_theme.as_ref() {
+            opt.syntax_theme = Some(syntax_theme.to_string());
+        }
+    }
+}
+
+/// Honor deprecated arguments by rewriting the canonical --*-style arguments if appropriate.
+// TODO: How to avoid repeating the default values for style options here and in
+// the structopt definition?
+fn rewrite_style_strings_to_honor_deprecated_minus_plus_options(opt: &mut cli::Opt) {
+    // If --highlight-removed was passed then we should set minus and minus emph foreground to
+    // "syntax", if they are still at their default values.
+    let deprecated_minus_foreground_arg = if opt.deprecated_highlight_minus_lines {
+        Some("syntax")
+    } else {
+        None
+    };
+
+    if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
+        &opt.minus_style,
+        ("normal", "auto"),
+        (
+            deprecated_minus_foreground_arg,
+            opt.deprecated_minus_background_color.as_deref(),
+        ),
+        "minus",
+    ) {
+        opt.minus_style = rewritten.to_string();
+    }
+    if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
+        &opt.minus_emph_style,
+        ("normal", "auto"),
+        (
+            deprecated_minus_foreground_arg,
+            opt.deprecated_minus_emph_background_color.as_deref(),
+        ),
+        "minus-emph",
+    ) {
+        opt.minus_emph_style = rewritten.to_string();
+    }
+    if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
+        &opt.plus_style,
+        ("syntax", "auto"),
+        (None, opt.deprecated_plus_background_color.as_deref()),
+        "plus",
+    ) {
+        opt.plus_style = rewritten.to_string();
+    }
+    if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
+        &opt.plus_emph_style,
+        ("syntax", "auto"),
+        (None, opt.deprecated_plus_emph_background_color.as_deref()),
+        "plus-emph",
+    ) {
+        opt.plus_emph_style = rewritten.to_string();
+    }
+}
+
+/// For backwards-compatibility, --{commit,file}-style box means --element-decoration-style 'box ul'.
+fn rewrite_options_to_implement_deprecated_commit_and_file_style_box_option(opt: &mut cli::Opt) {
+    if &opt.commit_style == "box" {
+        opt.commit_decoration_style = format!("box ul {}", opt.commit_decoration_style);
+        opt.commit_style.clear();
+    }
+    if &opt.file_style == "box" {
+        opt.file_decoration_style = format!("box ul {}", opt.file_decoration_style);
+        opt.file_style.clear();
+    }
+}
+
+fn rewrite_options_to_implement_deprecated_hunk_style_option(opt: &mut cli::Opt) {
+    // Examples of how --hunk-style was originally used are
+    // --hunk-style box       => --hunk-header-decoration-style box
+    // --hunk-style underline => --hunk-header-decoration-style underline
+    // --hunk-style plain     => --hunk-header-decoration-style ''
+    if opt.deprecated_hunk_style.is_some() {
+        // As in the other cases, we only honor the deprecated option if the replacement option has
+        // apparently been left at its default value.
+        let hunk_header_decoration_default = "blue box";
+        if opt.hunk_header_decoration_style != hunk_header_decoration_default {
+            eprintln!(
+                "Deprecated option --hunk-style cannot be used with --hunk-header-decoration-style. \
+                 Use --hunk-header-decoration-style.");
+            process::exit(1);
+        }
+        match opt.deprecated_hunk_style.as_deref().map(str::to_lowercase) {
+            Some(attr) if attr == "plain" => opt.hunk_header_decoration_style = "".to_string(),
+            Some(attr) if attr == "" => {}
+            Some(attr) => opt.hunk_header_decoration_style = attr,
+            None => {}
+        }
+        opt.deprecated_hunk_style = None;
+    }
+}
+
+fn _get_rewritten_commit_file_hunk_header_style_string(
+    style_default_pair: (&str, Option<&str>),
+    deprecated_args_style_pair: (Option<&str>, Option<&str>),
+) -> Option<String> {
+    let format_style = |pair: (&str, Option<&str>)| {
+        format!(
+            "{}{}",
+            pair.0,
+            match pair.1 {
+                Some(s) => format!(" {}", s),
+                None => "".to_string(),
+            }
+        )
+    };
+    match deprecated_args_style_pair {
+        (None, None) => None,
+        deprecated_args_style_pair => Some(format_style((
+            deprecated_args_style_pair.0.unwrap_or(style_default_pair.0),
+            match deprecated_args_style_pair.1 {
+                Some(s) => Some(s),
+                None => style_default_pair.1,
+            },
+        ))),
+    }
+}
+
+fn _get_rewritten_minus_plus_style_string(
+    style: &str,
+    style_default_pair: (&str, &str),
+    deprecated_args_style_pair: (Option<&str>, Option<&str>),
+    element_name: &str,
+) -> Option<String> {
+    let format_style = |pair: (&str, &str)| format!("{} {}", pair.0, pair.1);
+    match (style, deprecated_args_style_pair) {
+        (_, (None, None)) => None, // no rewrite
+        (style, deprecated_args_style_pair) if style == format_style(style_default_pair) => {
+            // TODO: We allow the deprecated argument values to have effect if
+            // the style argument value is equal to its default value. This is
+            // non-ideal, because the user may have explicitly supplied the
+            // style argument (i.e. it might just happen to equal the default).
+            Some(format_style((
+                deprecated_args_style_pair.0.unwrap_or(style_default_pair.0),
+                deprecated_args_style_pair.1.unwrap_or(style_default_pair.1),
+            )))
+        }
+        (_, (_, Some(_))) => {
+            eprintln!(
+                "--{name}-color cannot be used with --{name}-style. \
+                 Use --{name}-style=\"fg bg attr1 attr2 ...\" to set \
+                 foreground color, background color, and style attributes. \
+                 --{name}-color can only be used to set the background color. \
+                 (It is still available for backwards-compatibility.)",
+                name = element_name,
+            );
+            process::exit(1);
+        }
+        (_, (Some(_), None)) => {
+            eprintln!(
+                "Deprecated option --highlight-removed cannot be used with \
+                 --{name}-style. Use --{name}-style=\"fg bg attr1 attr2 ...\" \
+                 to set foreground color, background color, and style \
+                 attributes.",
+                name = element_name,
+            );
+            process::exit(1);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::ffi::OsString;
+
+    use structopt::{clap, StructOpt};
+
+    use crate::cli;
+    use crate::options::rewrite::apply_rewrite_rules;
+
+    #[test]
+    fn test_default_is_stable_under_rewrites() {
+        let mut opt = cli::Opt::from_iter(Vec::<OsString>::new());
+        let before = opt.clone();
+
+        apply_rewrite_rules(&mut opt, &clap::ArgMatches::new());
+
+        assert_eq!(opt, before);
+    }
+
+    /// Since --hunk-header-decoration-style is at its default value of "box",
+    /// the deprecated option is allowed to overwrite it.
+    #[test]
+    fn test_deprecated_hunk_style_is_rewritten() {
+        let mut opt = cli::Opt::from_iter(Vec::<OsString>::new());
+        opt.deprecated_hunk_style = Some("underline".to_string());
+        let default = "blue box";
+        assert_eq!(opt.hunk_header_decoration_style, default);
+        apply_rewrite_rules(&mut opt, &clap::ArgMatches::new());
+        assert_eq!(opt.deprecated_hunk_style, None);
+        assert_eq!(opt.hunk_header_decoration_style, "underline");
+    }
+
+    #[test]
+    fn test_deprecated_hunk_style_is_not_rewritten() {
+        let mut opt = cli::Opt::from_iter(Vec::<OsString>::new());
+        opt.deprecated_hunk_style = Some("".to_string());
+        let default = "blue box";
+        assert_eq!(opt.hunk_header_decoration_style, default);
+        apply_rewrite_rules(&mut opt, &clap::ArgMatches::new());
+        assert_eq!(opt.deprecated_hunk_style, None);
+        assert_eq!(opt.hunk_header_decoration_style, default);
+    }
+}