Respect --json in mensa tags

See #4.

src/main.rs

@@ -63,10 +63,9 @@
 use chrono::Duration;
 use directories_next::ProjectDirs;
 use lazy_static::lazy_static;
+use serde::Serialize;
 use structopt::StructOpt;
-use strum::IntoEnumIterator;
 use tracing::error;
-use unicode_width::UnicodeWidthStr;
 
 /// Colorizes the output.
 ///
@@ -170,7 +169,9 @@ fn real_main() -> Result<()> {
             let canteens = Canteen::fetch(&state)?;
             Canteen::print_all(&state, &canteens);
         }
-        Some(Command::Tags) => print_tags(&state),
+        Some(Command::Tags) => {
+            Tag::print_all(&state)?;
+        }
         None => {
             let cmd = MealsCommand::default();
             let state = State::from(state, &cmd);
@@ -181,38 +182,6 @@ fn real_main() -> Result<()> {
     Ok(())
 }
 
-fn print_tags<Cmd>(state: &State<Cmd>) {
-    for tag in Tag::iter() {
-        println!();
-        const ID_WIDTH: usize = 4;
-        const TEXT_INDENT: &str = "     ";
-        let emoji = if state.args.plain && tag.is_primary() {
-            format!("{:>width$}", "-", width = ID_WIDTH)
-        } else {
-            let emoji = tag.as_id(state);
-            let emoji_len = emoji.width();
-            format!(
-                "{}{}",
-                " ".repeat(ID_WIDTH.saturating_sub(emoji_len)),
-                emoji
-            )
-        };
-        let description_width = get_sane_terminal_dimensions().0;
-        let description = textwrap::fill(
-            tag.describe(),
-            textwrap::Options::new(description_width)
-                .initial_indent(TEXT_INDENT)
-                .subsequent_indent(TEXT_INDENT),
-        );
-        println!(
-            "{} {}\n{}",
-            color!(state: emoji; bright_yellow, bold),
-            color!(state: tag; bold),
-            color!(state: description; bright_black),
-        );
-    }
-}
-
 fn get_sane_terminal_dimensions() -> (usize, usize) {
     terminal_size::terminal_size()
         .map(|(w, h)| (w.0 as usize, h.0 as usize))
@@ -221,3 +190,10 @@ fn get_sane_terminal_dimensions() -> (usize, usize) {
         .log_warn()
         .unwrap_or((80, 80))
 }
+
+fn print_json<T: Serialize>(value: &T) -> Result<()> {
+    let stdout = std::io::stdout();
+    let output = stdout.lock();
+    serde_json::to_writer_pretty(output, value)
+        .map_err(|why| Error::Serializing(why, "writing meals as json"))
+}

src/meal/mod.rs

@@ -10,8 +10,8 @@ use std::collections::HashSet;
 use crate::{
     cache::fetch_json,
     config::{args::MealsCommand, MealsState, PriceTags},
-    error::{pass_info, Error, Result},
-    get_sane_terminal_dimensions,
+    error::{pass_info, Result},
+    get_sane_terminal_dimensions, print_json,
     tag::Tag,
     State, ENDPOINT,
 };
@@ -128,10 +128,7 @@ impl Meal {
         let favs = state.get_favs_rule();
         let meals = meals.iter().filter(|meal| filter.is_match(meal));
         if state.args.json {
-            let stdout = std::io::stdout();
-            let output = stdout.lock();
-            serde_json::to_writer_pretty(output, &meals.collect::<Vec<_>>())
-                .map_err(|why| Error::Serializing(why, "writing meals as json"))
+            print_json(&meals.collect::<Vec<_>>())
         } else {
             for meal in meals {
                 let is_fav = favs.is_match(meal);

src/tag.rs

@@ -1,10 +1,16 @@
+use std::collections::HashMap;
+
 use lazy_static::lazy_static;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 use regex::RegexSet;
 use serde::{Deserialize, Serialize};
-use strum::{Display, EnumIter};
+use strum::{Display, EnumIter, IntoEnumIterator};
+use unicode_width::UnicodeWidthStr;
 
-use crate::config::State;
+use crate::{config::State, error::Result, get_sane_terminal_dimensions, print_json};
+
+const ID_WIDTH: usize = 4;
+const TEXT_INDENT: &str = "     ";
 
 lazy_static! {
     /// These must have the same order as the variants in the [`Tag`] enum.
@@ -170,4 +176,69 @@ impl Tag {
             }
         }
     }
+
+    /// Print this tag.
+    ///
+    /// Does **not** respect `--json`, use [`Self::print_all`].
+    pub fn print<Cmd>(&self, state: &State<Cmd>) {
+        let emoji = if state.args.plain && self.is_primary() {
+            format!("{:>width$}", "-", width = ID_WIDTH)
+        } else {
+            let emoji = self.as_id(state);
+            let emoji_len = emoji.width();
+            format!(
+                "{}{}",
+                " ".repeat(ID_WIDTH.saturating_sub(emoji_len)),
+                emoji
+            )
+        };
+        let description_width = get_sane_terminal_dimensions().0;
+        let description = textwrap::fill(
+            self.describe(),
+            textwrap::Options::new(description_width)
+                .initial_indent(TEXT_INDENT)
+                .subsequent_indent(TEXT_INDENT),
+        );
+        println!(
+            "{} {}\n{}",
+            color!(state: emoji; bright_yellow, bold),
+            color!(state: self; bold),
+            color!(state: description; bright_black),
+        );
+    }
+
+    /// Print all tags.
+    pub fn print_all<Cmd>(state: &State<Cmd>) -> Result<()> {
+        if state.args.json {
+            Self::print_all_json(state)
+        } else {
+            for tag in Tag::iter() {
+                println!();
+                tag.print(state);
+            }
+            Ok(())
+        }
+    }
+
+    /// Print all tags as json.
+    ///
+    /// This will result in a list of objects containing the following keys:
+    /// - id: An identifier, like 'Vegan' or '22'
+    /// - name: The name of the tag.
+    /// - desc: A simple description.
+    ///
+    fn print_all_json<Cmd>(state: &State<Cmd>) -> Result<()> {
+        let tags: Vec<HashMap<&str, String>> = Tag::iter()
+            .map(|tag| {
+                vec![
+                    ("id", tag.as_id(state)),
+                    ("name", tag.to_string()),
+                    ("desc", tag.describe().to_owned()),
+                ]
+                .into_iter()
+                .collect()
+            })
+            .collect();
+        print_json(&tags)
+    }
 }