Feature: add forgit show command (#417)

Introducing `show` as a new subcommand of `forgit`, an interactive
version of `git show`. The configured default alias is `gso`.

Alt-T can be used to toggle between showing the diff and the commit
message in the fzf preview window.

The new command in used instead of `forgit diff` when pressing enter
in `forgit log`. This fixes the display of diffs for merge commits.

**Note**: we have a requirement for the `fzf` version now. The minimum
required `fzf` version is 0.49.0. If the installed version is lower,
forgit will exit with an error message.

Fixes #416.

Author: carlfriedrich

README.md

@@ -29,7 +29,13 @@ It's **lightweight** and **easy to use**.
 
 # 📥 Installation
 
-*Make sure you have [`fzf`](https://github.com/junegunn/fzf) installed.*
+## Requirements
+
+- [`fzf`](https://github.com/junegunn/fzf) version `0.49.0` or higher
+
+  If your OS package manager bundles an older version of `fzf`, you might install it using [`fzf`'s own install script'](https://github.com/junegunn/fzf?tab=readme-ov-file#using-git).
+
+## Shell package managers
 
 ``` zsh
 # for zplug
@@ -101,6 +107,8 @@ Then add the following to your shell's config file:
 
 - **Interactive `git diff` viewer** (`gd`)
 
+- **Interactive `git show` viewer** (`gso`)
+
 - **Interactive `git reset HEAD <file>` selector** (`grh`)
 
 - **Interactive `git checkout <file>` selector** (`gcf`)
@@ -172,6 +180,7 @@ You can change the default aliases by defining these variables below.
 forgit_log=glo
 forgit_reflog=grl
 forgit_diff=gd
+forgit_show=gso
 forgit_add=ga
 forgit_reset_head=grh
 forgit_ignore=gi
@@ -232,6 +241,7 @@ These are passed to the according `git` calls.
 | `glo`    | `FORGIT_LOG_GIT_OPTS`                                                       |
 | `grl`    | `FORGIT_REFLOG_GIT_OPTS`                                                    |
 | `gd`     | `FORGIT_DIFF_GIT_OPTS`                                                      |
+| `gso`     | `FORGIT_SHOW_GIT_OPTS`                                                      |
 | `grh`    | `FORGIT_RESET_HEAD_GIT_OPTS`                                                |
 | `gcf`    | `FORGIT_CHECKOUT_FILE_GIT_OPTS`                                             |
 | `gcb`    | `FORGIT_CHECKOUT_BRANCH_GIT_OPTS`, `FORGIT_CHECKOUT_BRANCH_BRANCH_GIT_OPTS` |
@@ -286,6 +296,7 @@ Customizing fzf options for each command individually is also supported:
 | `grl`    | `FORGIT_REFLOG_FZF_OPTS`          |
 | `gi`     | `FORGIT_IGNORE_FZF_OPTS`          |
 | `gd`     | `FORGIT_DIFF_FZF_OPTS`            |
+| `gso`    | `FORGIT_SHOW_FZF_OPTS`            |
 | `grh`    | `FORGIT_RESET_HEAD_FZF_OPTS`      |
 | `gcf`    | `FORGIT_CHECKOUT_FILE_FZF_OPTS`   |
 | `gcb`    | `FORGIT_CHECKOUT_BRANCH_FZF_OPTS` |

bin/git-forgit

@@ -12,6 +12,21 @@
 # This gives users the choice to set aliases inside of their git config instead
 # of their shell config if they prefer.
 
+# Check if fzf is installed
+installed_fzf_version=$(fzf --version 2>/dev/null | awk '{print $1}')
+if [[ -z "$installed_fzf_version" ]]; then
+    echo "fzf is not installed. Please install fzf first."
+    exit 1
+fi
+
+# Check fzf version
+required_fzf_version="0.49.0"
+higher_fzf_version=$(printf '%s\n' "$required_fzf_version" "$installed_fzf_version" | sort -V | tail -n1)
+if [[ "$higher_fzf_version" != "$installed_fzf_version" ]]; then
+    echo "fzf version $required_fzf_version or higher is required. You have $installed_fzf_version."
+    exit 1
+fi
+
 # Set shell for fzf preview commands
 # Disable shellcheck for "which", because it suggests "command -v xxx" instead,
 # which is not a working replacement.
@@ -185,7 +200,7 @@ _forgit_log_enter() {
     local sha
     sha=$(echo "$1" | _forgit_extract_sha)
     shift
-    echo "$sha" | xargs -I% "${FORGIT}" diff %^! "$@"
+    echo "$sha" | xargs -I% "${FORGIT}" show % "$@"
 }
 
 # git commit viewer
@@ -339,6 +354,83 @@ _forgit_diff() {
     return $fzf_exit_code
 }
 
+_forgit_exec_show() {
+    _forgit_show_git_opts=()
+    _forgit_parse_array _forgit_show_git_opts "$FORGIT_SHOW_GIT_OPTS"
+    git show --pretty="" --diff-merges=first-parent --color=always "${_forgit_show_git_opts[@]}" "$@"
+}
+
+_forgit_show_view() {
+    local input_line=$1
+    local diff_context=$2
+    local commit=$3
+    local repo
+    repo=$(git rev-parse --show-toplevel)
+    cd "$repo" || return 1
+    echo "$input_line" | _forgit_get_files_from_diff_line | xargs -0 \
+        "$FORGIT" exec_show "${commit}^{commit}" -U"$diff_context" -- | _forgit_pager diff
+}
+
+_forgit_show_preview() {
+    local input_line=$1
+    local diff_context=$2
+    local commit=$3
+    if [[ "$FZF_PREVIEW_LABEL" =~ "Diff" ]]; then
+        _forgit_show_view "${input_line}" "${diff_context}" "${commit}"
+    else
+        git show --quiet --color=always "${FZF_PROMPT%% *}"
+    fi
+}
+
+_forgit_show_enter() {
+    file=$1
+    commit=$2
+    _forgit_show_view "$file" "$_forgit_fullscreen_context" "${commit}"
+}
+
+# git show viewer
+_forgit_show() {
+    _forgit_inside_work_tree || return 1
+    local files opts commit escaped_commit
+    files=()
+    if [[ $# -ne 0 ]]; then
+        if git rev-parse "$1" -- &>/dev/null ; then
+            commit="$1" && files=("${@:2}")
+        else
+            commit="HEAD" && files=("$@")
+        fi
+    else
+        commit="HEAD"
+    fi
+    # Escape opening brackets to support stashes (see comment in _forgit_diff)
+    escaped_commit=${commit//\{/\\\\\{}
+    opts="
+        $FORGIT_FZF_DEFAULT_OPTS
+        +m -0 --bind=\"enter:execute($FORGIT show_enter {} $escaped_commit | $FORGIT pager enter)\"
+        --preview=\"$FORGIT show_preview {} '$_forgit_preview_context' $escaped_commit\"
+        --preview-label=\" Diff \"
+        --bind=\"alt-e:execute($FORGIT edit_diffed_file {})+refresh-preview\"
+        --bind=\"alt-t:transform:[[ ! \\\"\$FZF_PREVIEW_LABEL\\\" =~ 'Diff' ]] &&
+                echo 'change-preview-label( Diff )+refresh-preview' ||
+                echo 'change-preview-label( Commit Message )+refresh-preview'\"
+        $FORGIT_DIFF_FZF_OPTS
+        --prompt=\"${commit} > \"
+    "
+    _forgit_show_git_opts=()
+    _forgit_parse_array _forgit_show_git_opts "$FORGIT_SHOW_GIT_OPTS"
+    # Add "^{commit}" suffix after the actual commit. This suppresses the tag information in case it is a tag.
+    # See: https://git-scm.com/docs/git-show#Documentation/git-show.txt-codegitshow-s--formatsv100commitcode
+    git show --pretty="" --name-status --diff-merges=first-parent "${_forgit_show_git_opts[@]}" "${commit}^{commit}" \
+        -- "${files[@]}" |
+        sed -E 's/^([[:alnum:]]+)[[:space:]]+(.*)$/[\1]	\2/' |
+        sed 's/	/  ->  /2' | expand -t 8 |
+        FZF_DEFAULT_OPTS="$opts" fzf
+    fzf_exit_code=$?
+    # exit successfully on 130 (ctrl-c/esc)
+    [[ $fzf_exit_code == 130 ]] && return 0
+    return $fzf_exit_code
+}
+
 _forgit_add_preview() {
     file=$(echo "$1" | _forgit_get_single_file_from_add_line)
     if (git status -s -- "$file" | grep '^??') &>/dev/null; then  # diff with /dev/null for untracked files
@@ -1021,6 +1113,7 @@ public_commands=(
     "rebase"
     "reset_head"
     "revert_commit"
+    "show"
     "stash_show"
     "stash_push"
 )
@@ -1035,10 +1128,13 @@ private_commands=(
     "cherry_pick_preview"
     "clean_preview"
     "diff_enter"
+    "exec_show"
     "file_preview"
     "ignore_preview"
     "revert_preview"
     "reset_head_preview"
+    "show_enter"
+    "show_preview"
     "stash_push_preview"
     "stash_show_preview"
     "yank_sha"

completions/_git-forgit

@@ -97,6 +97,7 @@ _git-forgit() {
     reset_head) _git-staged ;;
     revert_commit) __git_recent_commits ;;
     stash_show) _git-stash-show ;;
+    show) _git-show ;;
     esac
 }
 
@@ -122,6 +123,7 @@ compdef _git-rebase forgit::rebase
 compdef _git-staged forgit::reset::head
 compdef __git_recent_commits forgit::revert::commit
 compdef _git-stash-show forgit::stash::show
+compdef _git-show forgit::show
 
 # this is the case of calling the command and pressing tab
 # the very first time of a shell session, we have to manually

completions/git-forgit.bash

@@ -75,6 +75,7 @@ _git_forgit()
         rebase
         reset_head
         revert_commit
+        show
         stash_show
         stash_push
     "
@@ -101,6 +102,7 @@ _git_forgit()
                 rebase) _git_rebase ;;
                 reset_head) _git_reset ;;
                 revert_commit) _git_revert ;;
+                show) _git_show ;;
                 stash_show) _git_stash_show ;;
             esac
             ;;
@@ -135,6 +137,7 @@ then
     __git_complete forgit::rebase _git_rebase
     __git_complete forgit::reset::head _git_reset
     __git_complete forgit::revert::commit _git_revert
+    __git_complete forgit::show _git_show
     __git_complete forgit::stash::show _git_stash_show
 
     # Completion for forgit plugin shell aliases
@@ -154,6 +157,7 @@ then
         __git_complete "${forgit_rebase}" _git_rebase
         __git_complete "${forgit_reset_head}" _git_reset
         __git_complete "${forgit_revert_commit}" _git_revert
+        __git_complete "${forgit_show}" _git_show
         __git_complete "${forgit_stash_show}" _git_stash_show
     fi
 fi

completions/git-forgit.fish

@@ -40,6 +40,7 @@ complete -c git-forgit -n __fish_forgit_needs_subcommand -a reflog -d 'git reflo
 complete -c git-forgit -n __fish_forgit_needs_subcommand -a rebase -d 'git rebase'
 complete -c git-forgit -n __fish_forgit_needs_subcommand -a reset_head -d 'git reset HEAD (unstage) selector'
 complete -c git-forgit -n __fish_forgit_needs_subcommand -a revert_commit -d 'git revert commit selector'
+complete -c git-forgit -n __fish_forgit_needs_subcommand -a show -d 'git show viewer'
 complete -c git-forgit -n __fish_forgit_needs_subcommand -a stash_show -d 'git stash viewer'
 complete -c git-forgit -n __fish_forgit_needs_subcommand -a stash_push -d 'git stash push selector'
 

conf.d/forgit.plugin.fish

@@ -37,6 +37,7 @@ if test -z "$FORGIT_NO_ALIASES"
     abbr -a -- (string collect $forgit_log; or string collect "glo") git-forgit log
     abbr -a -- (string collect $forgit_reflog; or string collect "grl") git-forgit reflog
     abbr -a -- (string collect $forgit_diff; or string collect "gd") git-forgit diff
+    abbr -a -- (string collect $forgit_show; or string collect "gso") git-forgit show
     abbr -a -- (string collect $forgit_ignore; or string collect "gi") git-forgit ignore
     abbr -a -- (string collect $forgit_checkout_file; or string collect "gcf") git-forgit checkout_file
     abbr -a -- (string collect $forgit_checkout_branch; or string collect "gcb") git-forgit checkout_branch

forgit.plugin.zsh

@@ -53,6 +53,10 @@ forgit::diff() {
     "$FORGIT" diff "$@"
 }
 
+forgit::show() {
+    "$FORGIT" show "$@"
+}
+
 forgit::add() {
     "$FORGIT" add "$@"
 }
@@ -146,6 +150,7 @@ if [[ -z "$FORGIT_NO_ALIASES" ]]; then
     export forgit_log="${forgit_log:-glo}"
     export forgit_reflog="${forgit_reflog:-grl}"
     export forgit_diff="${forgit_diff:-gd}"
+    export forgit_show="${forgit_show:-gso}"
     export forgit_ignore="${forgit_ignore:-gi}"
     export forgit_checkout_file="${forgit_checkout_file:-gcf}"
     export forgit_checkout_branch="${forgit_checkout_branch:-gcb}"
@@ -166,6 +171,7 @@ if [[ -z "$FORGIT_NO_ALIASES" ]]; then
     alias "${forgit_log}"='forgit::log'
     alias "${forgit_reflog}"='forgit::reflog'
     alias "${forgit_diff}"='forgit::diff'
+    alias "${forgit_show}"='forgit::show'
     alias "${forgit_ignore}"='forgit::ignore'
     alias "${forgit_checkout_file}"='forgit::checkout::file'
     alias "${forgit_checkout_branch}"='forgit::checkout::branch'