feat: with prepend as well

Signed-off-by: kjuulh <contact@kjuulh.io>

Cargo.lock

@@ -346,6 +346,8 @@ dependencies = [
  "conventional_commit_parser",
  "dotenv",
  "git-cliff-core",
+ "lazy_static",
+ "parse-changelog",
  "pretty_assertions",
  "regex",
  "reqwest",
@@ -815,6 +817,7 @@ checksum = "d5477fe2230a79769d8dc68e0eabf5437907c0457a5614a9e8dddb67f65eb65d"
 dependencies = [
  "equivalent",
  "hashbrown 0.14.0",
+ "serde",
 ]
 
 [[package]]
@@ -887,6 +890,12 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
+[[package]]
+name = "lexopt"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baff4b617f7df3d896f97fe922b64817f6cd9a756bb81d40f8883f2f66dcb401"
+
 [[package]]
 name = "libc"
 version = "0.2.147"
@@ -1110,6 +1119,22 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
 
+[[package]]
+name = "parse-changelog"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39a24196a65fc15a0a747df8c041abc5a009f2c09c550b0a14f7eeb0c10255ef"
+dependencies = [
+ "anyhow",
+ "indexmap 2.0.0",
+ "lexopt",
+ "memchr",
+ "once_cell",
+ "regex",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "parse-zoneinfo"
 version = "0.3.0"

Cargo.toml

@@ -20,6 +20,8 @@ reqwest = { version = "0.11.18" }
 git-cliff-core = "1.2.0"
 regex = "*"
 chrono = "*"
+lazy_static = "*"
+parse-changelog = "*"
 
 tracing-test = "0.2"
 pretty_assertions = "1.4"

crates/cuddle-please/Cargo.toml

@@ -19,6 +19,8 @@ tempdir.workspace = true
 git-cliff-core.workspace = true
 regex.workspace = true
 chrono.workspace = true
+lazy_static.workspace = true
+parse-changelog.workspace = true
 
 [dev-dependencies]
 tracing-test = { workspace = true, features = ["no-env-filter"] }

crates/cuddle-please/src/cliff/mod.rs

@@ -107,6 +107,31 @@ impl ChangeLog<'_> {
             .context("cannot convert bytes to string (contains non utf-8 char indices)")
     }
 
+    pub fn prepend(self, old_changelog: impl Into<String>) -> anyhow::Result<String> {
+        let old_changelog = old_changelog.into();
+        if let Ok(Some(last_version)) = changelog_parser::last_version_from_str(&old_changelog) {
+            let next_version = self
+                .release
+                .version
+                .as_ref()
+                .context("current release contains no version")?;
+            if next_version == &last_version {
+                return Ok(old_changelog);
+            }
+        }
+
+        let old_header = changelog_parser::parse_header(&old_changelog);
+        let config = self
+            .config
+            .clone()
+            .unwrap_or_else(|| self.default_config_with_header(old_header));
+        let changelog = Changelog::new(vec![self.release], &config)?;
+        let mut out = Vec::new();
+        changelog.prepend(old_changelog, &mut out)?;
+        String::from_utf8(out)
+            .context("cannot convert bytes to string (contains non utf-8 char indices)")
+    }
+
     fn default_config<'a>(&self) -> Config {
         let config = Config {
             changelog: default_changelog_config(
@@ -118,6 +143,18 @@ impl ChangeLog<'_> {
 
         config
     }
+
+    fn default_config_with_header<'a>(&self, header: Option<String>) -> Config {
+        let config = Config {
+            changelog: default_changelog_config(
+                header,
+                self.release_link.as_ref().map(|rl| rl.as_str()),
+            ),
+            git: default_git_config(),
+        };
+
+        config
+    }
 }
 
 fn default_git_config() -> GitConfig {
@@ -199,6 +236,245 @@ fn default_changelog_body_config(release_link: Option<&str>) -> String {
     }
 }
 
+mod changelog_parser {
+    use std::{fs::read_to_string, path::Path};
+
+    use anyhow::Context;
+    use regex::Regex;
+
+    /// Parse the header from a changelog.
+    /// The changelog header is a string at the begin of the changelog that:
+    /// - Starts with `# Changelog`, `# CHANGELOG`, or `# changelog`
+    /// - ends with `## Unreleased`, `## [Unreleased]` or `## ..anything..`
+    ///   (in the ..anything.. case, `## ..anything..` is not included in the header)
+    pub fn parse_header(changelog: &str) -> Option<String> {
+        lazy_static::lazy_static! {
+            static ref FIRST_RE: Regex = Regex::new(r#"(?s)^(# Changelog|# CHANGELOG|# changelog)(.*)(## Unreleased|## \[Unreleased\])"#).unwrap();
+
+            static ref SECOND_RE: Regex = Regex::new(r#"(?s)^(# Changelog|# CHANGELOG|# changelog)(.*)(\n## )"#).unwrap();
+        }
+        if let Some(captures) = FIRST_RE.captures(changelog) {
+            return Some(format!("{}\n", &captures[0]));
+        }
+
+        if let Some(captures) = SECOND_RE.captures(changelog) {
+            return Some(format!("{}{}", &captures[1], &captures[2]));
+        }
+
+        None
+    }
+
+    pub fn last_changes(changelog: &Path) -> anyhow::Result<Option<String>> {
+        let changelog = read_to_string(changelog).context("can't read changelog file")?;
+        last_changes_from_str(&changelog)
+    }
+
+    pub fn last_changes_from_str(changelog: &str) -> anyhow::Result<Option<String>> {
+        let parser = ChangelogParser::new(changelog)?;
+        let last_release = parser.last_release().map(|r| r.notes.to_string());
+        Ok(last_release)
+    }
+
+    pub fn last_version_from_str(changelog: &str) -> anyhow::Result<Option<String>> {
+        let parser = ChangelogParser::new(changelog)?;
+        let last_release = parser.last_release().map(|r| r.version.to_string());
+        Ok(last_release)
+    }
+
+    pub fn last_release_from_str(changelog: &str) -> anyhow::Result<Option<ChangelogRelease>> {
+        let parser = ChangelogParser::new(changelog)?;
+        let last_release = parser.last_release().map(ChangelogRelease::from_release);
+        Ok(last_release)
+    }
+
+    pub struct ChangelogRelease {
+        title: String,
+        notes: String,
+    }
+
+    impl ChangelogRelease {
+        fn from_release(release: &parse_changelog::Release) -> Self {
+            Self {
+                title: release.title.to_string(),
+                notes: release.notes.to_string(),
+            }
+        }
+
+        pub fn title(&self) -> &str {
+            &self.title
+        }
+
+        pub fn notes(&self) -> &str {
+            &self.notes
+        }
+    }
+
+    pub struct ChangelogParser<'a> {
+        changelog: parse_changelog::Changelog<'a>,
+    }
+
+    impl<'a> ChangelogParser<'a> {
+        pub fn new(changelog_text: &'a str) -> anyhow::Result<Self> {
+            let changelog =
+                parse_changelog::parse(changelog_text).context("can't parse changelog")?;
+            Ok(Self { changelog })
+        }
+
+        fn last_release(&self) -> Option<&parse_changelog::Release> {
+            let last_release = release_at(&self.changelog, 0)?;
+            let last_release = if last_release.version.to_lowercase().contains("unreleased") {
+                release_at(&self.changelog, 1)?
+            } else {
+                last_release
+            };
+            Some(last_release)
+        }
+    }
+
+    fn release_at<'a>(
+        changelog: &'a parse_changelog::Changelog,
+        index: usize,
+    ) -> Option<&'a parse_changelog::Release<'a>> {
+        let release = changelog.get_index(index)?.1;
+        Some(release)
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        fn last_changes_from_str_test(changelog: &str) -> String {
+            last_changes_from_str(changelog).unwrap().unwrap()
+        }
+
+        #[test]
+        fn changelog_header_is_parsed() {
+            let changelog = "\
+# Changelog
+
+My custom changelog header
+
+## [Unreleased]
+";
+            let header = parse_header(changelog).unwrap();
+            let expected_header = "\
+# Changelog
+
+My custom changelog header
+
+## [Unreleased]
+";
+            assert_eq!(header, expected_header);
+        }
+
+        #[test]
+        fn changelog_header_without_unreleased_is_parsed() {
+            let changelog = "\
+# Changelog
+
+My custom changelog header
+
+## [0.2.5] - 2022-12-16
+";
+            let header = parse_header(changelog).unwrap();
+            let expected_header = "\
+# Changelog
+
+My custom changelog header
+";
+            assert_eq!(header, expected_header);
+        }
+
+        #[test]
+        fn changelog_header_with_versions_is_parsed() {
+            let changelog = "\
+# Changelog
+
+My custom changelog header
+
+## [Unreleased]
+
+## [0.2.5] - 2022-12-16
+";
+            let header = parse_header(changelog).unwrap();
+            let expected_header = "\
+# Changelog
+
+My custom changelog header
+
+## [Unreleased]
+";
+            assert_eq!(header, expected_header);
+        }
+
+        #[test]
+        fn changelog_header_isnt_recognized() {
+            // A two-level header similar to `## [Unreleased]` is missing
+            let changelog = "\
+# Changelog
+
+My custom changelog header
+";
+            let header = parse_header(changelog);
+            assert_eq!(header, None);
+        }
+
+        #[test]
+        fn changelog_with_unreleased_section_is_parsed() {
+            let changelog = "\
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [0.2.5] - 2022-12-16
+
+### Added
+- Add function to retrieve default branch (#372)
+
+## [0.2.4] - 2022-12-12
+
+### Changed
+- improved error message
+";
+            let changes = last_changes_from_str_test(changelog);
+            let expected_changes = "\
+### Added
+- Add function to retrieve default branch (#372)";
+            assert_eq!(changes, expected_changes);
+        }
+
+        #[test]
+        fn changelog_without_unreleased_section_is_parsed() {
+            let changelog = "\
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.2.5](https://github.com/MarcoIeni/release-plz/compare/git_cmd-v0.2.4...git_cmd-v0.2.5) - 2022-12-16
+
+### Added
+- Add function to retrieve default branch (#372)
+
+## [0.2.4] - 2022-12-12
+
+### Changed
+- improved error message
+";
+            let changes = last_changes_from_str_test(changelog);
+            let expected_changes = "\
+### Added
+- Add function to retrieve default branch (#372)";
+            assert_eq!(changes, expected_changes);
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;