#!/usr/bin/env bash

# ugit: Undo your last oopsie in Git
# 

set -uo pipefail;

SCRIPT_NAME="$0"
SCRIPT_URL="https://github.com/Bhupesh-V/ugit/releases/latest/download/ugit"
TMP_FILE="/tmp/ugit.sh"
VERSION="1.0"

installed() {
    cmd=$(command -v "${1}")

    [[ -n "${cmd}" ]] && [[ -f "${cmd}" ]]
    return ${?}
}

die() {
    >&2 echo "Fatal: ${@}"
    exit 1
}

[[ "${BASH_VERSINFO[0]}" -lt 3 ]] && die "Bash >=3 required"

deps=(fzf git awk xargs cut nl tput)
for dep in "${deps[@]}"; do
    installed "${dep}" || die "Missing dependency: '${dep}'"
done

printf "%s\n" "$(tput bold)Undo your last oopsie in Git 🙈️$(tput sgr0)"

display_menu() {
    printf "%s\n" "Undo [git commit]"
    printf "%s\n" "Undo [git push]"
    printf "%s\n" "Undo [git add]"
    printf "%s\n" "Undo [git pull]"
    printf "%s\n" "Undo/Change [git commit message]"
    printf "%s\n" "Undo local branch delete [git branch -d]"
    printf "%s\n" "Undo [git reset]"
    printf "%s\n" "Undo a Merge with Conflicts"
    printf "%s\n" "Undo an Unpushed Merge Commit"
    printf "%s\n" "Undo a Pushed Merge Commit"
    printf "%s\n" "Undo [git stash pop/drop/clear]"
    printf "%s\n" "Undo [git stash apply]"
    printf "%s\n" "Undo [git tag -d] tag delete"
    printf "%s\n" "Undo [git rebase]"
    printf "%s\n" "Undo/Recover commited file delete"
    printf "%s\n" "Undo/Recover uncommited file delete"
    printf "%s\n" "Undo/Restore file to a previous commit/version"
}


undo_git_commit() {
    # TODO: ask which commit to undo?
    git reset HEAD~
    # undo last commit (don't unstage everything)
    # git reset --soft HEAD^
}

do_git_reset() {
    # FROM: https://stackoverflow.com/questions/1223354/undo-git-pull-how-to-bring-repos-to-old-state
    FZF_HEADER=${1:-"Choose last good branch commit"}
    last_good_state=$(git reflog | fzf --ansi --height 20% --reverse --header="$FZF_HEADER" | awk '{print $1}')
    # check if working tree is clean or not
    [[ $(git status --porcelain 2>/dev/null) ]] && read -p "You have uncommited changes, still proceed? [Y/n]: " -n 1 -r USER_INPUT
    USER_INPUT=${USER_INPUT:-Y}
    [[ "$USER_INPUT" == Y ]] && git reset --hard "$last_good_state"
}

undo_git_add() {
    # show prompt to unstage files interactively
    choices=$(git ls-files | fzf --height 10% --reverse --multi --marker='🢂' --color 'marker:#B8CC52' --header="Choose Files to unstage (TAB to select)")
    git restore --staged $choices
}

change_commit_message() {
    printf "%s" "Enter New Commit Message (Ctrl+d to save):"
    msg=$(</dev/stdin)
    echo
    [[ "$msg" ]] && git commit --amend -m "$msg" || printf "%s" "Empty Commit string!"
}

undo_git_push() {
    commit=$(git log --oneline | fzf --ansi --height 10% --reverse --multi --header="Choose Commit hash to revert/undo" | awk '{print $1}')
    if git revert "$commit"; then
        printf "%s\n" "Commit: $commit successfully reverted."
        printf "%s\n" "Make sure to run 'git push' now"
    fi
}

undo_branch_delete() {
    # undo local branch delete
    last_branch_commit=$(git reflog | fzf --ansi --height 20% --reverse --multi --header="Choose last good branch commit" | awk '{print $1}')
    # echo "$last_branch_commit"
    read -p "Enter Branch Name: " -r BRANCH_NAME
    if git checkout -b "$BRANCH_NAME" "$last_branch_commit"; then
        printf "%s\n" "Branch $BRANCH_NAME successfully recovered"
    fi
}

undo_git_reset() {
    LAST_GOOD_STATE=$(git reflog | fzf --ansi --height 20% --reverse --multi --header="Choose last known good commit" | awk '{print $1}')
    git reset "$LAST_GOOD_STATE"
}

undo_git_merge() {
    # Undoing a git merge is a messy business
    printf "%s\n" "Tips: "
    printf "%s\n" "Do a revert of the previous revert if the faulty side branch was fixed by adding corrections on top."
    printf "%s\n" "Re-merge the result branch if the faulty side branch (discarded by an earlier revert of a merge) was rebuilt from scratch (i.e. rebasing and fixing)."
    if [[ "$1" == "conflicts" ]]; then
        git merge --abort
    elif [[ "$1" == "unpushed" ]]; then
        # FROM: https://stackoverflow.com/questions/1223354/undo-git-pull-how-to-bring-repos-to-old-state
        # last_good_state=$(git reflog | fzf --ansi --height 20% --reverse --header="Choose the merge commit" | awk '{print $1}')
        # check if working tree is clean or not
        [[ $(git status --porcelain 2>/dev/null) ]] && read -p "You have uncommited changes, still proceed? [Y/n]: " -n 1 -r USER_INPUT
        USER_INPUT=${USER_INPUT:-Y}
        # ref: ORIG_HEAD points to the original commit from before the merge
        [[ "$USER_INPUT" == Y ]] && git reset --merge ORIG_HEAD || exit 0
        # [[ "$USER_INPUT" == Y ]] && git reset --merge "$last_good_state" || exit 0
    else
        default_branch=$(git remote show origin | awk '/HEAD/ {print $3}')
        printf "%s\n" "Switching to default branch $default_branch"
        git checkout "$default_branch"
        commit=$(git log --oneline | fzf --ansi --height 10% --reverse --header="Choose the merge commit" | awk '{print $1}')
        if git revert -m 1 "$commit"; then
            printf "%s\n" "Merge ($commit) successfully reverted"
        fi
    fi
}

recover_lost_stash() {
    LOST_STASH=$(git fsck --no-progress --unreachable | grep commit | cut -d ' ' -f3 | xargs git log --oneline --merges --no-walk | fzf --ansi --height 20% --reverse --header="Choose commit associated with stash" | awk '{print $1}')
    read -p "Enter Stash Message/Comment: " -r STASH_MSG
    if git update-ref refs/stash "$LOST_STASH" --create-reflog -m "$STASH_MSG"; then
        printf "%s\n" "Stash Successfully Recovered"
        git stash list | grep "$STASH_MSG"
    fi
}

undo_git_stash_apply() {
    # check if diff coloring is set to auto in git config if not the reverse apply command will fail
    is_diff_color=$(git config --get color.diff | tr -d '\n')
    if [[ "$is_diff_color" == "auto" ]]; then
        if git stash show -p | git apply --reverse; then
            printf "%s\n" "Done 👍️"
        fi
    else
        printf "%s\n" "Please change diff color to auto in .gitconfig & run ugit again"
        printf "%s\n" "Or use the following command [git config --global color.diff \"auto\"]"
    fi
}

recover_deleted_tag() {
    # only works for annotated tags? :(
    printf "%s\n\n" "Note: Only annotated tags can be restored"

    read -p "Enter lost Tag name (e.g v1.2): " -r TAG_NAME
    COMMIT=$(git fsck --no-progress --unreachable --tags | awk '/tagged/ {print $6}')

    [[ -z "$COMMIT" ]] && printf "%s\n" "Unable to find any deleted tags :(" && exit 1

    OBJECT_TYPE=$(git cat-file -t "$COMMIT")
    DELETED_TAG=$(git cat-file -p "$COMMIT" | awk '/tag / {print$2;exit;}')

    if [[ "$OBJECT_TYPE" == "tag" && "$DELETED_TAG" != "$TAG_NAME" ]]; then
        printf "%s" "Input tag name $TAG_NAME doesn't match with previously deleted tag $DELETED_TAG"
    elif git update-ref refs/tags/"$TAG_NAME" --create-reflog "$COMMIT"; then
        printf "%s\n" "Tag $TAG_NAME Successfully Recovered 👍️"
    else
        printf "%s\n" "Unable to recover deleted tag $TAG_NAME"
    fi
}

undo_file_delete() {
    if [[ "$1" == "uncommited" ]]; then
        # user didn't commit the file deletion
        DELETED_FILE=$(git ls-files -d | fzf --ansi --height 20% --reverse --header="Choose deleted file to recover" | awk '{print $1}')
        if git checkout HEAD "$DELETED_FILE"; then
            printf "%s\n" "$DELETED_FILE Successfully Recovered 👍️"
            exit 0
        fi
    fi
    read -p "Enter complete filename: " -r FILENAME
    COMMIT=$(git log --diff-filter=D --oneline | fzf --ansi --height 20% --reverse --header="Choose commit that deleted $FILENAME" | awk '{print $1}')
    if git checkout "$COMMIT"~1 -- "$FILENAME"; then
        printf "%s\n" "$FILENAME Successfully Recovered 👍️"
    fi
}

restore_file() {
    FILE=$(git ls-files | fzf --ansi --height 20% --reverse --header="Choose file to restore" | awk '{print $1}')
    COMMIT=$(git log --oneline "$FILE" | fzf --ansi --height 80% --reverse --prompt="Choose commit to restore file to" --header="Use ctrl-j/ctrl-k to navigate file preview. ctrl+space to toggle preview" --preview "echo {} | cut -d' ' -f1 | xargs -I{} git show {}:$FILE" --bind 'j:down,k:up,ctrl-j:preview-down,ctrl-k:preview-up,ctrl-space:toggle-preview' --preview-window down:60%)
    COMMIT=$(printf "%s" "$COMMIT" | awk '{print $1}')

    if ! git diff -s --quiet "$FILE"; then
        # check if any local changes
        printf "%s\n" "$FILE seems to be modified. Please either commit or discard those changes."
        exit 0
    elif git restore --source="$COMMIT" "$FILE"; then
        printf "%s\n" "$FILE restored to version at $COMMIT"
    fi
}

ugit_menu() {
    case $option in
        1) undo_git_commit;;
        2) undo_git_push;;
        3) undo_git_add;;
        4) undo_git_merge "unpushed";;
        5) change_commit_message;;
        6) undo_branch_delete;;
        7) undo_git_reset;;
        8) undo_git_merge "conflicts";;
        9) do_git_reset;;
        10) undo_git_merge "pushed";;
        11) recover_lost_stash;;
        12) undo_git_stash_apply;;
        13) recover_deleted_tag;;
        14) do_git_reset "Choose commit just before rebase started";;
        15) undo_file_delete;;
        16) undo_file_delete "uncommited";;
        17) restore_file;;
    esac
}

show_version() {
    printf "ugit version %s\n" "$VERSION"
}

print_help() {
    cat <<EOF
Usage: $(basename "${BASH_SOURCE[0]}") [-h] [-v] [-u]

ugit helps you undo your last git command without much effort
Just run 'ugit' and search for what you want to undo

Available options:

-h, --help      Print this help and exit
-v, --version   Print current ugit version
-u, --update    Update ugit
EOF
    printf "\n%s\n" "Contact 📬️: varshneybhupesh@gmail.com for assistance"
    printf "%s\n" "Read the guide: https://bhupesh.gitbook.io/notes/git/how-to-undo-anything-in-git"
}

ugit_update() {
    printf "%s\n" "Checking for updates ..."
    curl -s -L "$SCRIPT_URL" > "$TMP_FILE"
    NEW_VER=$(grep "^VERSION" "$TMP_FILE" | awk -F'[="]' '{print $3}')

    if [[ "$VERSION" < "$NEW_VER" ]]; then
        printf "Updating ugit \e[31;1m%s\e[0m -> \e[32;1m%s\e[0m\n" "$VERSION" "$NEW_VER"
        chmod +x "$TMP_FILE"
        # WIP
        if cp "$TMP_FILE" "$SCRIPT_NAME"; then printf "%s\n" "Done"; fi
        rm -f "$TMP_FILE"
    else
        printf "%s\n" "ugit is already at the latest version ($VERSION)"
        rm -f "$TMP_FILE"
    fi
    exit 0
}

main() {
    if [[ $# -gt 0 ]]; then
        local key="$1"
        case "$key" in
            --version|-v)
                show_version
                ;;
            --update|-u)
                ugit_update
                ;;
            --help|-h)
                print_help
                exit
                ;;
            *)
                printf "%s\n" "ERROR: Unrecognized argument $key"
                exit 1
                ;;
        esac
    else
        option=$(display_menu | nl -n ln | fzf --header="Don't worry we all mess up sometimes" --height 30% --reverse --pointer='ᐅ' --cycle | awk '{print $1}')
        ugit_menu
    fi
}

main "$@"