From a6242e9166f573dbffd48814750e6184363f2499 Mon Sep 17 00:00:00 2001
From: Sebastian Wiesner <sebastian@swsnr.de>
Date: Wed, 6 Nov 2024 10:50:54 +0100
Subject: [PATCH] Remove mime_guess dependency

---
 CHANGELOG.md                               |  5 +++++
 Cargo.lock                                 | 11 ----------
 Cargo.toml                                 |  1 +
 pulldown-cmark-mdcat/Cargo.toml            |  2 +-
 pulldown-cmark-mdcat/src/resources/file.rs | 25 +++++++++++++++++++++-
 supply-chain/config.toml                   |  4 ----
 6 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7f7999a5..d2658ee6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,11 @@ Use `cargo release` to create a new release.
 
 ## [Unreleased]
 
+### Removed
+- Remove a few dependencies: `mime_guess` (see [GH-297]).
+
+[GH-297]: https://github.com/swsnr/mdcat/pull/297
+
 ## [2.5.0] – 2024-09-26
 
 ### Changed
diff --git a/Cargo.lock b/Cargo.lock
index b5560f33..3d1e2777 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1254,16 +1254,6 @@ version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
-[[package]]
-name = "mime_guess"
-version = "2.0.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f7c44f8e672c00fe5308fa235f821cb4198414e1c77935c1ab6948d3fd78550e"
-dependencies = [
- "mime",
- "unicase",
-]
-
 [[package]]
 name = "minimal-lexical"
 version = "0.2.1"
@@ -1682,7 +1672,6 @@ dependencies = [
  "insta",
  "mdcat-http-reqwest",
  "mime",
- "mime_guess",
  "pulldown-cmark",
  "regex",
  "resvg",
diff --git a/Cargo.toml b/Cargo.toml
index fddee80f..3dd4db69 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -28,6 +28,7 @@ pulldown-cmark-mdcat = { workspace = true, default-features = true }
 reqwest = { workspace = true }
 shell-words = { version = "1.1.0", default-features = false, features = ["std"] }
 syntect = { workspace = true, features = ["regex-fancy", "default-syntaxes"] }
+# TODO: Drop system_proxy
 system_proxy = { version = "0.3.2", default-features = false }
 tracing = { workspace = true }
 tracing-subscriber = { version = "0.3.18", default-features = false, features = ["env-filter", "std", "fmt", "ansi"] }
diff --git a/pulldown-cmark-mdcat/Cargo.toml b/pulldown-cmark-mdcat/Cargo.toml
index a64422e1..8481bb87 100644
--- a/pulldown-cmark-mdcat/Cargo.toml
+++ b/pulldown-cmark-mdcat/Cargo.toml
@@ -24,10 +24,10 @@ onig = ["syntect/regex-onig"]
 base64 = { version = "0.22.1", default-features = false, features = ["std"] }
 anstyle = { version = "1.0.7", default-features = false }
 mime = { workspace = true }
-mime_guess = { version = "2.0.5", default-features = false }
 pulldown-cmark = { workspace = true }
 syntect = { workspace = true, features = ["parsing"] }
 textwrap = { version = "0.16.1", default-features = false, features = ["unicode-linebreak", "unicode-width"] }
+# TODO: Drop this-error?
 thiserror = { version = "1.0.61", default-features = false }
 tracing = { workspace = true }
 url = "2.5.2"
diff --git a/pulldown-cmark-mdcat/src/resources/file.rs b/pulldown-cmark-mdcat/src/resources/file.rs
index c3f0ce5b..34927c79 100644
--- a/pulldown-cmark-mdcat/src/resources/file.rs
+++ b/pulldown-cmark-mdcat/src/resources/file.rs
@@ -9,7 +9,9 @@
 use std::fs::File;
 use std::io::prelude::*;
 use std::io::{Error, ErrorKind, Result};
+use std::path::Path;
 
+use mime::Mime;
 use tracing::{event, instrument, Level};
 use url::Url;
 
@@ -30,6 +32,27 @@ impl FileResourceHandler {
     }
 }
 
+/// Guess a mimetype, in so far as mdcat makes use of the mime type.
+///
+/// This function recognizes
+///
+/// - SVG images because mdcat needs to render SVG images explicitly, and
+/// - PNG images because kitty can pass through PNG images in some cases.
+///
+/// It checks mime types exclusively by looking at the lowercase extension.
+///
+/// It ignores all other extensions and mime types and returns `None` in these cases.
+fn guess_mimetype<P: AsRef<Path>>(path: P) -> Option<Mime> {
+    path.as_ref()
+        .extension()
+        .map(|s| s.to_ascii_lowercase())
+        .and_then(|s| match s.to_str() {
+            Some("png") => Some(mime::IMAGE_PNG),
+            Some("svg") => Some(mime::IMAGE_SVG),
+            _ => None,
+        })
+}
+
 impl ResourceUrlHandler for FileResourceHandler {
     #[instrument(level = "debug", skip(self))]
     fn read_resource(&self, url: &Url) -> Result<MimeData> {
@@ -54,7 +77,7 @@ impl ResourceUrlHandler for FileResourceHandler {
                             format!("Contents of {url} exceeded {} bytes", self.read_limit),
                         ))
                     } else {
-                        let mime_type = mime_guess::from_path(&path).first();
+                        let mime_type = guess_mimetype(&path);
                         if mime_type.is_none() {
                             event!(
                                 Level::DEBUG,
diff --git a/supply-chain/config.toml b/supply-chain/config.toml
index 39d8a07d..0eecd328 100644
--- a/supply-chain/config.toml
+++ b/supply-chain/config.toml
@@ -292,10 +292,6 @@ criteria = "safe-to-run"
 version = "0.9.5"
 criteria = "safe-to-run"
 
-[[exemptions.mime_guess]]
-version = "2.0.5"
-criteria = "safe-to-run"
-
 [[exemptions.minimal-lexical]]
 version = "0.2.1"
 criteria = "safe-to-run"