feat: implement Pandoc conversion plugin

plugins/pandoc/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "convertis-pandoc"
+build = "../../plugin-build.rs"
+version = "0.1.0"
+description = "Pandoc plugin for Convertis"
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[package.metadata.convertis]
+id = "pandoc"
+api-version = 2
+debian-dependencies = ["pandoc"]
+rpm-dependencies = ["/usr/bin/pandoc"]
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+convertis-plugin-api.workspace = true

plugins/pandoc/src/lib.rs

@@ -0,0 +1,68 @@
+// Copyright (C) 2026 Elias Wendland <eliaswendland@pm.me>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 3 exclusively.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use convertis_plugin_api::{Conversion, ConversionRequest, Plugin, PluginMetadata};
+use std::process::Command;
+
+const INPUTS: &[&str] = &["md", "html", "pdf", "docx", "ltx", "epub"];
+const OUTPUTS: &[&str] = &["pdf", "html", "ltx", "md", "docx", "epub"];
+struct Pandoc;
+
+impl Plugin for Pandoc {
+    fn metadata(&self) -> PluginMetadata {
+        PluginMetadata {
+            id: "pandoc".into(),
+            package: "convertis-pandoc".into(),
+            description: "Pandoc document conversion".into(),
+            conversions: INPUTS
+                .iter()
+                .flat_map(|from| {
+                    OUTPUTS
+                        .iter()
+                        .filter(move |to| to != &from)
+                        .map(move |to| Conversion::file(from, to, (240, 210, 180)))
+                })
+                .collect(),
+            options: vec![],
+        }
+    }
+    fn availability(&self) -> Result<(), String> {
+        Command::new("pandoc")
+            .arg("--version")
+            .output()
+            .map_err(|_| "'pandoc' is required".to_owned())
+            .and_then(|output| {
+                output
+                    .status
+                    .success()
+                    .then_some(())
+                    .ok_or_else(|| "'pandoc' is unavailable".to_owned())
+            })
+    }
+    fn convert(&self, request: &ConversionRequest) -> Result<(), String> {
+        let output = Command::new("pandoc")
+            .arg(&request.input)
+            .arg("-o")
+            .arg(&request.output)
+            .output()
+            .map_err(|error| error.to_string())?;
+
+        if output.status.success() {
+            Ok(())
+        } else {
+            Err(String::from_utf8_lossy(&output.stderr).into_owned())
+        }
+    }
+}
+convertis_plugin_api::export_plugin!(Pandoc, "pandoc");