#!/bin/bash

warn() {
    echo "$1" >&2
}

die() {
    warn "fatal: $1"
    exit 3
}

usage() {
    warn "usage: $0 [options] COPR_PROJECT"
    warn ""
    warn "Options:"
    warn ""
    warn "  -n      dry mode, don't do anything (just show"
    warn "          what would be done)"
    warn "  -r REL  use REL as Release number in SPEC file"
    warn "  -v VER  use VER as Version number in SPEC file"
    warn "  -u URL  use URL as base (to get last tag and"
    warn "          compose Source0 in SPEC file)"
    warn ""
    warn "If -r or -v are not specified, git-describe master"
    warn "is consulted."
    exit 2
}

last_version() {
    git ls-remote --tag "$UrlBase" \
      | grep '/tags/' \
      | cut -d/ -f3 \
      | sort -V \
      | tail -1 \
      | sed "s/^v//"
}

trigger() {
    sed -e "
        /^Version/ s|__SLOP_VERSION__|$Version|
        /^Release/ s|__SLOP_RELEASE__|$Release|
        /^Source0/ s|__SLOP_URLBASE__|$UrlBase|
    " <slop.spec.in >"$Tmp/slop.spec"
    copr build "$CoprProject" "$Tmp/slop.spec"
}

git_guess() {
    #
    # Print git-guessed $1
    #
    local what=$1   # what we want (ver|rel)
    local describe  # full git-describe output
    local xtra=     # extra part (-N-gHASH)
    local num=0     # num. of commits since tag (N)
    local sha=      # '.g'+sha1 of this commit (gHASH)
    describe=$(git describe --tags --always HEAD)
    case $describe in
        *-*)                        #     v1.2.3-21-g654cba
            tag=${describe%%-*}     # tag=v1.2.3
            xtra=${describe#$tag-}  # xtra=-21-g654cba
            num=${xtra%%-*}         # num=21
            sha=.${xtra#$num-}      # sha=.g654cba
            ;;
        *)
            tag=$describe
            ;;
    esac
    case $what in
        ver)    echo "${tag#v}"         ;;
        rel)    echo "$((num + 1))$sha" ;;
    esac
}

main() {
    local Version       # Version in SPEC file
    local Release       # Release in SPEC file
    local CoprProject   # COPR project
    local UrlBase       # GitHub URL base
    local Tmp           # our temp
    local Branch        # branch to use, if empty, tags are considered
    local DryRun=false  # do not do anything
    UrlBase=https://github.com/AloisMahdal/slop
    Tmp=$(mktemp -d)
    while true; do case $1 in
        -b) Branch=$2;      shift 2 || usage ;;
        -u) UrlBase=$2;     shift 2 || usage ;;
        -r) Release=$2;     shift 2 || usage ;;
        -v) Version=${2#v}; shift 2 || usage ;;
        -n) DryRun=true;    shift ;;
        -*) usage ;;
        *)  break ;;
    esac done
    CoprProject=$1
    test -n "$CoprProject" || usage
    which copr >/dev/null \
     || die "copr not found, try 'sudo install python-copr'"
    if test -n "$Branch"; then
        die "not implemented"
        test -n "$Version" || Version=$(git_guess ver)
        test -n "$Release" || Release=$(git_guess rel)
    else
        test -n "$Version" || Version=$(last_version)
        test -n "$Release" || Release=1
    fi
    $DryRun && {
        warn "dry mode active, we would build:"
        warn "    at $CoprProject"
        test -n "$Branch" && warn "    using branch $Branch"
        test -n "$Branch" || warn "    using last tag"
        warn "    from $UrlBase"
        warn "    yielding slop-$Version-$Release.*.rpm"
        exit 1
    }
    trigger
    rm -rf "$Tmp"
}

main "$@"