Fixed changes() count extractor: files, insertions, deletions

[starlocke]

The original changes() method did not do a proper extraction when a commit contained ONLY deletions. This remedies that.

[dreamyguy]

Thanks for taking the time to improve Gitlogg!

I ran a diff between the original output and the proposed output (the one I get after your changes).

I did it by running diff --speed-large-files output1.json output2.json.

I observed some inconsistencies, so I isolated a commit. This is the output of an actual commit, which I anonymized.

// Output - original:
{"repository":"anonymized.git","commit_nr":116,"commit_hash":"7c4184283a6dfe624aa12d0a711fe1ad6792f869","author_name":"Anonimized","author_email":"anonymized@anonymized.com","author_date":"Fri Sep 2 11:37:08 2016 +0200","author_date_relative":"3 years, 1 month ago","author_date_unix_timestamp":"1472809028","author_date_iso_8601":"2016-09-02 11:37:08 +0200","subject":"anonymized","subject_sanitized":"anonymized","stats":" 1 file changed, 1 insertion(+), 1 deletion(-)","time_hour":11,"time_minutes":37,"time_seconds":8,"time_gmt":"+0200","date_day_week":"Fri","date_month_day":2,"date_month_name":"Sep","date_month_number":9,"date_year":"2016","date_iso_8601":"2016-09-02","files_changed":1,"insertions":1,"deletions":1,"impact":0};

// Output - proposed:
{"repository":"anonymized.git","commit_nr":116,"commit_hash":"7c4184283a6dfe624aa12d0a711fe1ad6792f869","author_name":"Anonimized","author_email":"anonymized@anonymized.com","author_date":"Fri Sep 2 11:37:08 2016 +0200","author_date_relative":"3 years, 1 month ago","author_date_unix_timestamp":"1472809028","author_date_iso_8601":"2016-09-02 11:37:08 +0200","subject":"anonymized","subject_sanitized":"anonymized","stats":" 1 file changed, 1 insertion(+), 1 deletion(-)","time_hour":11,"time_minutes":37,"time_seconds":8,"time_gmt":"+0200","date_day_week":"Fri","date_month_day":2,"date_month_name":"Sep","date_month_number":9,"date_year":"2016","date_iso_8601":"2016-09-02","files_changed":0,"insertions":0,"deletions":0,"impact":0};

So I decided to dig deeper, by reproducing the relevant part within gitlog-parse-json.js:

// slice the string as long as it's not empty
const sliceit = (str) => {
    if (str === undefined) {
        return '';
    } else if (str !== '') {
        return str.slice(1);
    }
    return str;
};

// massage the stats
const changesOriginal = (data, index) => {
    const v = data.split(',')[index] || 0;
    let w = 0;
    if (v !== 0) {
        w = v.split(' ')[1]; // the number of changes is second on the array
    }
    return parseInt(w, 10);
};

// massage the stats
const changesProposed = (data, index) => {
    let v = 0;
    let m = null;
    if (index === 0) {
        // "files"
        m = data.match(/ [0-9]+ files/);
        if (m != null) v = m[0];
    }
    if (index === 1) {
        // "insertions"
        m = data.match(/ [0-9]+ insertions/);
        if (m != null) v = m[0];
    }
    if (index === 2) {
        // "deletions"
        m = data.match(/ [0-9]+ deletions/);
        if (m != null) v = m[0];
    }
    let w = 0;
    if (v !== 0) {
        w = v.split(' ')[1]; // the number of changes is second on the array
    }
    return parseInt(w, 10);
};

const returnStatsOriginal = (inp) => {
    const stats = sliceit(inp);
    const filesChanged = changesOriginal(stats, 0);
    const insertions = changesOriginal(stats, 1);
    const deletions = changesOriginal(stats, 2);
    return `{
        filesChanged: ${filesChanged},
        insertions: ${insertions},
        deletions: ${deletions},
    }`;
};

const returnStatsProposed = (inp) => {
    const stats = sliceit(inp);
    const filesChanged = changesProposed(stats, 0);
    const insertions = changesProposed(stats, 1);
    const deletions = changesProposed(stats, 2);
    return `{
        filesChanged: ${filesChanged},
        insertions: ${insertions},
        deletions: ${deletions},
    }`;
};

// Input:
const input = '  1 file changed, 1 insertion(+), 1 deletion(-)';

console.log(returnStatsOriginal(input));

// {
//     filesChanged: 1,
//     insertions: 1,
//     deletions: 1,
// }

console.log(returnStatsProposed(input));

// {
//     filesChanged: 0,
//     insertions: 0,
//     deletions: 0,
// }

This didn't output correct values, but you were definitely in the right track as I could see that the original function failed with:

const input = ' 2827 files changed, 664411 deletions(-)';

// {
//     filesChanged: NaN,
//     insertions: 664411,
//     deletions: 0,
// }

Testing it locally with Quokka.js, I was able to do further changes and verify them. After a few changes the function now works as intended. Thanks a lot for your contribution!

[dreamyguy]

@starlocke these are my changes, for reference: https://github.com/dreamyguy/gitlogg/commit/0bb7b25b3b47e073ebf998e830fe8b7956ed6556. Thanks again for the PR! 🙌