Update `--doctor` handling for *PAGER environment variables

1 files changed, 51 insertions, 25 deletions

diff --git a/src/subcommands/doctor/pager_env.rs b/src/subcommands/doctor/pager_env.rs
index 1784cef4..eb1fe0b6 100644
--- a/src/subcommands/doctor/pager_env.rs
+++ b/src/subcommands/doctor/pager_env.rs
@@ -9,46 +9,61 @@ pub struct PagerEnvVars {
     env_vars: HashMap<String, String>,
 }
 
-const UNSUPPORTED_PAGER_SUFFIX: &str = "PAGER";
+const PAGER_ENV_VARS: [&str; 4] = ["PAGER", "DELTA_PAGER", "BAT_PAGER", "GIT_PAGER"];
 
 impl PagerEnvVars {
     pub fn probe() -> Self {
         PagerEnvVars {
             env_vars: env::vars()
-                .filter(|(k, _)| k.ends_with(UNSUPPORTED_PAGER_SUFFIX))
+                .filter_map(|(k, v)| get_env_kv(k, v))
+                .into_iter()
                 .collect(),
         }
     }
+
+    fn selected_pager_is_less(&self) -> Option<bool> {
+        match self.env_vars.get("DELTA_PAGER") {
+            Some(_v) => Some(val_contains_less(_v)),
+            None => match self.env_vars.get("BAT_PAGER") {
+                Some(_v) => Some(val_contains_less(_v)),
+                None => match self.env_vars.get("PAGER") {
+                    Some(_v) => Some(val_contains_less(_v)),
+                    None => None,
+                },
+            },
+        }
+    }
 }
 
 impl Diagnostic for PagerEnvVars {
     fn report(&self) -> String {
-        let output_str = self
-            .env_vars
-            .iter()
-            .map(|(k, v)| format!("- {} = {}", k, v))
-            .collect::<Vec<String>>()
-            .join("\n");
-        "`*PAGER` environment variables: \n".to_string() + &output_str
+        let vars = &self.env_vars;
+        match self.selected_pager_is_less() {
+            Some(v) => match v {
+                true => "Your selected pager is `less`".to_owned(),
+                false => {
+                    let vars_str = vars
+                        .iter()
+                        .map(|(k, v)| format!(" - {} = {}", k, v))
+                        .collect::<Vec<String>>()
+                        .join("\n");
+                    return "The pager specified by your *PAGER environment variables is not `less`. You have:\n".to_owned() + &vars_str;
+                }
+            },
+            None => "Your selected pager is the system `less`".to_owned(),
+        }
     }
 
     fn diagnose(&self) -> Health {
-        let diagnosis_prefix = "Unsupported `*PAGER` environment variables are set: \n".to_string();
-        let remedy_prefix = "Unset `*PAGER` environment variables: \n".to_string();
-
-        let output_str_items = self
-            .env_vars
-            .iter()
-            .map(|(k, v)| format!("- {} = {}", k, v))
-            .collect::<Vec<String>>()
-            .join("\n");
-
-        match self.env_vars.keys().len() > 0 {
-            true => Unhealthy(
-                diagnosis_prefix + &*output_str_items,
-                remedy_prefix + &*output_str_items,
-            ),
-            false => Healthy,
+        let diagnosis = self.report();
+        let remedy = "Set `DELTA_PAGER` to your preferred version of `less`, or unset it to use the system `less`.".to_string();
+
+        match self.selected_pager_is_less() {
+            Some(v) => match v {
+                true => Healthy,
+                false => Unhealthy(diagnosis, remedy),
+            },
+            None => Healthy,
         }
     }
 
@@ -59,3 +74,14 @@ impl Diagnostic for PagerEnvVars {
         }
     }
 }
+
+fn get_env_kv(k: String, v: String) -> Option<(String, String)> {
+    match PAGER_ENV_VARS.contains(&k.as_str()) {
+        true => Some((k, v)),
+        false => None,
+    }
+}
+
+fn val_contains_less(val: &str) -> bool {
+    return val.to_ascii_lowercase().contains("less");
+}