#!/bin/bash

. "$MKIT_DIR/include/ini.sh" || die "cannot import ini.sh"

git_fact() {
    #
    # Get git fact $1
    #
    local fact_name="$1"
    git_present || warn "can't give fact outside git repo: $fact_name"
    case "$fact_name" in
        latest_tag)
            git log --format="%D" \
              | sed 's/,/\n/g' \
              | sed 's/^[[:blank:]]*//; ' \
              | grep -E '^tag: v[[:digit:]]+\.' \
              | cut -d' ' -f2 \
              | head -1
            ;;
        latest_version)
            git_fact latest_tag | git_tag2ver
            ;;
        current_branch)
            git rev-parse --abbrev-ref HEAD
            ;;
        reldiff)
            git log --oneline "$(git_fact latest_tag)..HEAD" --name-only
            ;;
        latest_sha)
            git log -1 --pretty=format:%h HEAD
            ;;
        *)
            warn "unknown git fact asked: $fact_name"
            ;;
    esac
}

git_present() {
    #
    # True if we're in a git repo
    #
    git rev-parse HEAD >&/dev/null
}

git_tag2ver() {
    #
    # Convert tag to version
    #
    sed s/^v//
}

git_ver2tag() {
    #
    # Convert version to tag
    #
    sed s/^/v/
}

git_lasthash() {
    #
    # Show last commit hash (with .dirty suffix if needed)
    #
    # If outside git repo, get it from .mkit/git_lasthash, which
    # should have been put there by dist target.  (I.e., this won't
    # work if you got outside the git repo in other way than dist
    # target, but that's actually expected.)
    #
    if git_present;
    then    # we are in git repo
        local last_hash=$(git rev-parse HEAD)
        if test "$(git diff --shortstat 2>/dev/null)" != "";
        then    # the tree is "dirty", i.e. has been edited
            local suffix=.dirty
        fi
        local suffix=""
        echo -n "$last_hash$suffix"
    else    # we are outside (eg. distributor's build dir')
        grep . .mkit/git_lasthash || {
            echo UNKNOWN
            warn "malformed source, could not determine git hash"
        }
    fi
}

semver() {
    #
    # Build semver version string with build metadata
    #
    # Build version string from available info using following
    # logic:
    #
    #  1. use project.version (from mkit.ini)
    #  2. if we are in git, override the version with last tag
    #  3. if set, add project:prerl (from mkit.ini) as pre-release ID
    #     (afer dash)
    #  4. if we are at a later commit than the last tag, add branch
    #     name and commit sha1 to build metadata (after plus sign)
    #  5. if the tree is "dirty", i.e. has uncommited changes,
    #     add "dirty" to build metadata
    #
    # The version is compatible with SemVer 2.0.0.
    #
    # Examples:
    #
    #     myprog v1.0.7                         # all clear
    #     myprog v1.0.7-alpha                   # mkit.ini: project:prerl="alpha"
    #     myprog v1.0.7-alpha+g1aef811.master   # ^^ + some commits after
    #     myprog v1.0.7-alpha+gf14fc4f.api2     # ^^ + on a feature branch
    #     myprog v1.0.7-alpha+gf14fc4f.api2.dirty  # ^^ + tree edited
    #     myprog v1.0.7-alpha+dirty             # tag OK but tree edited
    #     myprog v1.0.7+dirty                   # ^^ but no pre-release id
    #
    # Note that versions with "dirty" should be perceived as kind of
    # dangerous outside developer's own machine.  Versions with sha1 are
    # safer but must not be released.
    #
    # I have considered decorating the git commit refs to make them
    # sort of sortable (e.g. "r1.g1aef811"), but on second thought,
    # I don't think it's good idea to give *any* semantics to meta-data
    # at all.  First, there is no rule that r1<r2<r3; a commit can be
    # removing what other just added and one change can be split to
    # multiple commits.  Also, the whole thing breaks anyway once you
    # rebase your branch (no, it's not a sin).  The sole purpose of
    # meta-data is to *identify* the code, and provide safe path back
    # to tree; commit refs are already perfect for that.
    #
    # FIXME:  Using project:prerl for release IDs may not be compatible with
    #         release strategy implemented in release.sh
    #
    local version=$(ini 1value project:version)
    local prerl=$(ini 1value project:prerl)
    grep ":" <<<"$prerl" && warn "colon in project:prerl may corrupt version data: $prerl"
    if git_present;
    then    # we are in git repo... so we can get smart
        local latest_tag=$(git_fact latest_tag)
        if ! git describe --tags --exact-match HEAD >&/dev/null;
        then    # we are at a later commit than the last tag
            local commit="$(git_fact current_branch).g$(git_fact latest_sha)"
        fi
        if test "$(git diff --shortstat 2>/dev/null)" != "";
        then    # the tree is "dirty", i.e. has been edited
            local dirty=dirty
        fi
        test -n "$latest_tag" && version=${latest_tag:1}
        local suffix=""
        case "$commit:$dirty" in
            :)       suffix=""                ;;
            :dirty)  suffix="+$dirty"         ;;
            *:)      suffix="+$commit"        ;;
            *:dirty) suffix="+$commit.$dirty" ;;
        esac
        test -b "$prerl" && suffix="-$prerl$suffix"
        version="$version$suffix"
    fi
    echo "$version"
}