Add option to preserve file modification time when writing tags.

Issue #21

ChangeLog

@@ -1,6 +1,7 @@
 0.4.0
 -----
 1. Add action to export results from database to files.
+2. Add option to preserve file modification time when writing tags.
 
 0.3.0
 -----

UserGuide.md

@@ -150,6 +150,8 @@ in mixes. See the `Ignore` section later on for more details.
 * `tags` specifies whether analysis results should be written to, and re-read from,
 files. Set to `true` or `false`. If enabled, then results are stored in a `COMMENT`
 tag that starts with `BLISS_ANALYSIS`
+* `preserve` specifies whether file modification time should be preserved when
+writing tags. Set to `true` or `false`.
 
 
 Command-line parameters
@@ -173,6 +175,7 @@ tracks are to be analysed and how many old tracks are left in the database.
 * `-J` / `--json` JSONRPC port number of your LMS server.
 * `-n` / `--numtracks` Specify maximum number of tracks to analyse.
 * `-T` / `--tags` Write analysis results to file tags, and read from file tags.
+* `-p' / '--preserve` Attempt to preserve file modification time when writing tags.
 
 Equivalent items specified in the INI config file (detailed above) will override
 any specified on the commandline.

src/analyse.rs

@@ -161,7 +161,7 @@ fn show_errors(failed: &mut Vec<String>, tag_error: &mut Vec<String>) {
 }
 
 #[cfg(not(feature = "ffmpeg"))]
-fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max_threads: usize, use_tags: bool) -> Result<()> {
+fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max_threads: usize, use_tags: bool, preserve_mod_times: bool) -> Result<()> {
     let total = track_paths.len();
     let progress = ProgressBar::new(total.try_into().unwrap()).with_style(
         ProgressStyle::default_bar()
@@ -237,7 +237,7 @@ fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max
                             tag_error.push(sname.clone());
                         }
                         if use_tags {
-                            tags::write_analysis(&cpath, &track.analysis);
+                            tags::write_analysis(&cpath, &track.analysis, preserve_mod_times);
                         }
                         db.add_track(&sname, &meta, &track.analysis);
                     }
@@ -259,7 +259,7 @@ fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max
 }
 
 #[cfg(feature = "ffmpeg")]
-fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max_threads: usize, use_tags: bool) -> Result<()> {
+fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max_threads: usize, use_tags: bool, preserve_mod_times: bool) -> Result<()> {
     let total = track_paths.len();
     let progress = ProgressBar::new(total.try_into().unwrap()).with_style(
         ProgressStyle::default_bar()
@@ -292,7 +292,7 @@ fn analyse_new_files(db: &db::Db, mpath: &PathBuf, track_paths: Vec<String>, max
                     tag_error.push(sname.clone());
                 }
                 if use_tags {
-                    tags::write_analysis(&cpath, &track.analysis);
+                    tags::write_analysis(&cpath, &track.analysis, preserve_mod_times);
                 }
                 db.add_track(&sname, &meta, &track.analysis);
                 analysed += 1;
@@ -405,7 +405,7 @@ fn analyse_new_cue_tracks(db:&db::Db, mpath: &PathBuf, cue_tracks:Vec<cue::CueTr
     Ok(())
 }
 
-pub fn analyse_files(db_path: &str, mpaths: &Vec<PathBuf>, dry_run: bool, keep_old: bool, max_num_files: usize, max_threads: usize, ignore_path: &PathBuf, use_tags: bool) {
+pub fn analyse_files(db_path: &str, mpaths: &Vec<PathBuf>, dry_run: bool, keep_old: bool, max_num_files: usize, max_threads: usize, ignore_path: &PathBuf, use_tags: bool, preserve_mod_times: bool) {
     let mut db = db::Db::new(&String::from(db_path));
 
     db.init();
@@ -450,7 +450,7 @@ pub fn analyse_files(db_path: &str, mpaths: &Vec<PathBuf>, dry_run: bool, keep_o
             }
         } else {
             if !track_paths.is_empty() {
-                match analyse_new_files(&db, &mpath, track_paths, max_threads, use_tags) {
+                match analyse_new_files(&db, &mpath, track_paths, max_threads, use_tags, preserve_mod_times) {
                     Ok(_) => { changes_made = true; }
                     Err(e) => { log::error!("Analysis returned error: {}", e); }
                 }
@@ -482,10 +482,10 @@ pub fn read_tags(db_path: &str, mpaths: &Vec<PathBuf>) {
     db.close();
 }
 
-pub fn export(db_path: &str, mpaths: &Vec<PathBuf>) {
+pub fn export(db_path: &str, mpaths: &Vec<PathBuf>, preserve_mod_times: bool) {
     let db = db::Db::new(&String::from(db_path));
     db.init();
-    db.export(&mpaths);
+    db.export(&mpaths, preserve_mod_times);
     db.close();
 }
 

src/db.rs

@@ -344,7 +344,7 @@ impl Db {
         }
     }
 
-    pub fn export(&self, mpaths: &Vec<PathBuf>) {
+    pub fn export(&self, mpaths: &Vec<PathBuf>, preserve_mod_times: bool) {
         let total = self.get_track_count();
         if total > 0 {
             let progress = ProgressBar::new(total.try_into().unwrap()).with_style(
@@ -377,7 +377,7 @@ impl Db {
                             let spath = String::from(track_path.to_string_lossy());
                             let meta = tags::read(&spath, true);
                             if  meta.is_empty() || meta.analysis.is_none() || meta.analysis.unwrap()!=dbtags.analysis {
-                                tags::write_analysis(&spath, &dbtags.analysis);
+                                tags::write_analysis(&spath, &dbtags.analysis, preserve_mod_times);
                                 updated+=1;
                             }
                             break;

src/main.rs

@@ -42,6 +42,7 @@ fn main() {
     let mut music_paths: Vec<PathBuf> = Vec::new();
     let mut max_threads: usize = 0;
     let mut use_tags = false;
+    let mut preserve_mod_times = false;
 
     match dirs::home_dir() {
         Some(path) => {
@@ -76,6 +77,7 @@ fn main() {
         arg_parse.refer(&mut max_num_files).add_option(&["-n", "--numfiles"], Store, "Maximum number of files to analyse");
         arg_parse.refer(&mut max_threads).add_option(&["-t", "--threads"], Store, "Maximum number of threads to use for analysis");
         arg_parse.refer(&mut use_tags).add_option(&["-T", "--tags"], StoreTrue, "Read/write analysis results from/to source files");
+        arg_parse.refer(&mut preserve_mod_times).add_option(&["-p", "--preserve"], StoreTrue, "Preserve modification time when writing tags to files");
         arg_parse.refer(&mut task).add_argument("task", Store, "Task to perform; analyse, tags, ignore, upload, export, stopmixer.");
         arg_parse.parse_args_or_exit();
     }
@@ -147,6 +149,10 @@ fn main() {
                         Some(val) => { use_tags = val.eq("true"); }
                         None => { }
                     }
+                    match config.get(TOP_LEVEL_INI_TAG, "preserve") {
+                        Some(val) => { preserve_mod_times = val.eq("true"); }
+                        None => { }
+                    }
                 }
                 Err(e) => {
                     log::error!("Failed to load config file. {}", e);
@@ -207,10 +213,10 @@ fn main() {
                 }
                 analyse::update_ignore(&db_path, &ignore_path);
             } else if task.eq_ignore_ascii_case("export") {
-                analyse::export(&db_path, &music_paths);
+                analyse::export(&db_path, &music_paths, preserve_mod_times);
             } else {
                 let ignore_path = PathBuf::from(&ignore_file);
-                analyse::analyse_files(&db_path, &music_paths, dry_run, keep_old, max_num_files, max_threads, &ignore_path, use_tags);
+                analyse::analyse_files(&db_path, &music_paths, dry_run, keep_old, max_num_files, max_threads, &ignore_path, use_tags, preserve_mod_times);
             }
         }
     }

src/tags.rs

@@ -12,8 +12,11 @@ use lofty::file::FileType;
 use lofty::prelude::{Accessor, AudioFile, ItemKey, TagExt, TaggedFileExt};
 use lofty::tag::{ItemValue, Tag, TagItem};
 use regex::Regex;
+use std::fs::File;
+use std::fs;
 use std::path::Path;
 use substring::Substring;
+use std::time::SystemTime;
 use bliss_audio::{Analysis, AnalysisIndex};
 
 const MAX_GENRE_VAL: usize = 192;
@@ -22,7 +25,7 @@ const ANALYSIS_TAG:ItemKey = ItemKey::Comment;
 const ANALYSIS_TAG_START: &str = "BLISS_ANALYSIS";
 const ANALYSIS_TAG_VER: u16 = 1;
 
-pub fn write_analysis(track: &String, analysis: &Analysis) {
+pub fn write_analysis(track: &String, analysis: &Analysis, preserve_mod_times: bool) {
     let value = format!("{},{},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24},{:.24}", ANALYSIS_TAG_START, ANALYSIS_TAG_VER,
                         analysis[AnalysisIndex::Tempo], analysis[AnalysisIndex::Zcr], analysis[AnalysisIndex::MeanSpectralCentroid], analysis[AnalysisIndex::StdDeviationSpectralCentroid], analysis[AnalysisIndex::MeanSpectralRolloff],
                         analysis[AnalysisIndex::StdDeviationSpectralRolloff], analysis[AnalysisIndex::MeanSpectralFlatness], analysis[AnalysisIndex::StdDeviationSpectralFlatness], analysis[AnalysisIndex::MeanLoudness], analysis[AnalysisIndex::StdDeviationLoudness],
@@ -58,7 +61,23 @@ pub fn write_analysis(track: &String, analysis: &Analysis) {
 
         // Store analysis results
         tag.push(TagItem::new(ANALYSIS_TAG, ItemValue::Text(value)));
+        let now = SystemTime::now();
+        let mut mod_time = now;
+        if preserve_mod_times {
+            if let Ok(fmeta) = fs::metadata(track) {
+                if let Ok(time) = fmeta.modified() {
+                    mod_time = time;
+                }
+            }
+        }
         let _ = tag.save_to_path(Path::new(track), WriteOptions::default());
+        if preserve_mod_times {
+            if mod_time<now {
+                if let Ok(f) = File::open(track) {
+                    let _ = f.set_modified(mod_time);
+                }
+            }
+        }
     }
 }