#!/usr/bin/env bash

PROG=semtag
PROG_VERSION="v0.1.0"

SEMVER_REGEX="^v?(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(\-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$"
IDENTIFIER_REGEX="^\-([0-9A-Za-z-]+)\.([0-9A-Za-z-]+)*$"

# Global variables
FIRST_VERSION="v0.0.0"
finalversion=$FIRST_VERSION
lastversion=$FIRST_VERSION
hasversiontag="false"
scope="patch"
displayonly="false"
forcetag="false"
forcedversion=
versionname=
identifier=

HELP="\
Usage:
  $PROG
  $PROG getlast
  $PROG getfinal
  $PROG (final|alpha|beta|candidate) [-s <scope> (major|minor|patch|auto) | -o]
  $PROG --help
  $PROG --version
Options:
  -s         The scope that must be increased, can be major, minor or patch.
               The resulting version will match X.Y.Z(-PRERELEASE)(+BUILD)
               where X, Y and Z are positive integers, PRERELEASE is an optionnal
               string composed of alphanumeric characters describing if the build is
               a release candidate, alpha or beta version, with a number.
               BUILD is also an optional string composed of alphanumeric
               characters and hyphens.
               Setting the scope as 'auto', the script will chose the scope between
               'minor' and 'patch', depending on the amount of lines added (<10% will
               choose patch).
  -v         Specifies manually the version to be tagged, must be a valid semantic version
               in the format X.Y.Z where X, Y and Z are positive integers.
  -o         Output the version only, shows the bumped version, but doesn't tag.
  -f         Forces to tag, even if there are unstaged or uncommited changes.
Commands:
  --help     Print this help message.
  --version  Prints the program's version.
  get        Returns both current final version and last tagged version.
  getlast    Returns the latest tagged version.
  getfinal   Returns the latest tagged final version.
  getcurrent Returns the current version, based on the latest one, if there are uncommited or
               unstaged changes, they will be reflected in the version, adding the number of
               pending commits, current branch and commit hash.
  final      Tags the current build as a final version, this only can be done on the master branch.
  candidate  Tags the current build as a release candidate, the tag will contain all
               the commits from the last final version.
  alpha      Tags the current build as an alpha version, the tag will contain all
               the commits from the last final version.
  beta       Tags the current build as a beta version, the tag will contain all
               the commits from the last final version."

# Commands and options
ACTION="getlast"
ACTION="$1"
shift

# We get the parameters
while getopts "v:s:of" opt; do
  case $opt in
    v)
      forcedversion="$OPTARG"
      ;;
    s)
      scope="$OPTARG"
      ;;
    o)
      displayonly="true"
      ;;
    f)
      forcetag="true"
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2
      exit 1
      ;;
  esac
done

# Gets a string with the version and returns an array of maximum size of 5 with all the parts of the sematinc version
# $1 The string containing the version in semantic format
# $2 The variable to store the result array:
#      position 0: major number
#      position 1: minor number
#      position 2: patch number
#      position 3: identifier (or prerelease identifier)
#      position 4: build info
function explode_version {
  local __version=$1
  local __result=$2
  if [[ $__version =~ $SEMVER_REGEX ]] ; then
    local __major=${BASH_REMATCH[1]}
    local __minor=${BASH_REMATCH[2]}
    local __patch=${BASH_REMATCH[3]}
    local __prere=${BASH_REMATCH[4]}
    local __build=${BASH_REMATCH[5]}
    eval "$__result=(\"$__major\" \"$__minor\" \"$__patch\" \"$__prere\" \"$__build\")"
  else
    eval "$__result="
  fi
}

# Compare two versions and returns -1, 0 or 1
# $1 The first version to compare
# $2 The second version to compare
# $3 The variable where to store the result
function compare_versions {
  local __first
  local __second
  explode_version $1 __first
  explode_version $2 __second
  local lv=$3

  # Compares MAJOR, MINOR and PATCH
  for i in 0 1 2; do
    local __numberfirst=${__first[$i]}
    local __numbersecond=${__second[$i]}
    case $(($__numberfirst - $__numbersecond)) in
      0)
        ;;
      -[0-9]*)
        eval "$lv=-1"
        return 0
        ;;
      [0-9]*)
        eval "$lv=1"
        return 0
        ;;
    esac
  done

  # Identifiers should compare with the ASCII order.
  local __identifierfirst=${__first[3]}
  local __identifiersecond=${__second[3]}
  if [[ -n "$__identifierfirst" ]] && [[ -n "$__identifiersecond" ]]; then
    if [[ "$__identifierfirst" > "$__identifiersecond" ]]; then
      eval "$lv=1"
      return 0
    elif [[ "$__identifierfirst" < "$__identifiersecond" ]]; then
      eval "$lv=-1"
      return 0
    fi
  elif [[ -z "$__identifierfirst" ]] && [[ -n "$__identifiersecond" ]]; then
    eval "$lv=1"
    return 0
  elif [[ -n "$__identifierfirst" ]] && [[ -z "$__identifiersecond" ]]; then
    eval "$lv=-1"
    return 0
  fi

  eval "$lv=0"
}

# Returns the last version of two
# $1 The first version to compare
# $2 The second version to compare
# $3 The variable where to store the last one
function get_latest_of_two {
  local __first=$1
  local __second=$2
  local __result
  local __latest=$3
  compare_versions $__first $__second __result
  case $__result in
    0)
      eval "$__latest=$__second"
      ;;
    -1)
      eval "$__latest=$__second"
      ;;
    1)
      eval "$__latest=$__first"
      ;;
  esac
}

# Assigns a 2 size array with the identifier, having the identifier at pos 0, and the number in pos 1
# $1 The identifier in the format -id.#
# $2 The vferiable where to store the 2 size array
function explode_identifier {
  local __identifier=$1
  local __result=$2
  if [[ $__identifier =~ $IDENTIFIER_REGEX ]] ; then
    local __id=${BASH_REMATCH[1]}
    local __number=${BASH_REMATCH[2]}
    if [[ -z "$__number" ]]; then
      __number=1
    fi
    eval "$__result=(\"$__id\" \"$__number\")"
  else
    eval "$__result="
  fi
}

# Gets a list of tags and assigns the base and latest versions
# Receives an array with the tags containing the versions
# Assigns to the global variables finalversion and lastversion the final version and the latest version
function get_latest {
  local __taglist=("$@")
  local __tagsnumber=${#__taglist[@]}
  local __current
  case $__tagsnumber in
    0)
      finalversion=$FIRST_VERSION
      lastversion=$FIRST_VERSION
      ;;
    1)
      __current=${__taglist[0]}
      explode_version $__current ver
      if [ -n "$ver" ]; then
        if [ -n "${ver[3]}" ]; then
          finalversion=$FIRST_VERSION
        else
          finalversion=$__current
        fi
        lastversion=$__current
      else
        finalversion=$FIRST_VERSION
        lastversion=$FIRST_VERSION
      fi
      ;;
    *)
      local __lastpos=$(($__tagsnumber-1))
      for i in $(seq 0 $__lastpos)
      do
        __current=${__taglist[i]}
        explode_version ${__taglist[i]} ver
        if [ -n "$ver" ]; then
          if [ -z "${ver[3]}" ]; then
            get_latest_of_two $finalversion $__current finalversion
            get_latest_of_two $lastversion $finalversion lastversion
          else
            get_latest_of_two $lastversion $__current lastversion
          fi
        fi
      done
      ;;
  esac

  if git rev-parse -q --verify "refs/tags/$lastversion" >/dev/null; then
    hasversiontag="true"
  else
    hasversiontag="false"
  fi
}

# Gets the next version given the provided scope
# $1 The version that is going to be bumped
# $2 The scope to bump
# $3 The variable where to stoer the result
function get_next_version {
  local __exploded
  local __fromversion=$1
  local __scope=$2
  local __result=$3
  explode_version $__fromversion __exploded
  case $__scope in
    major)
      __exploded[0]=$((${__exploded[0]}+1))
      __exploded[1]=0
      __exploded[2]=0
    ;;
    minor)
      __exploded[1]=$((${__exploded[1]}+1))
      __exploded[2]=0
    ;;
    patch)
      __exploded[2]=$((${__exploded[2]}+1))
    ;;
  esac

  eval "$__result=v${__exploded[0]}.${__exploded[1]}.${__exploded[2]}"
}

function bump_version {
  ## First we try to get the next version based on the existing last one
  if [ "$scope" == "auto" ]; then
    get_scope_auto scope
  fi

  local __candidatefromlast=$FIRST_VERSION
  local __explodedlast
  explode_version $lastversion __explodedlast
  if [[ -n "${__explodedlast[3]}" ]]; then
    # Last version is not final
    local __idlast
    explode_identifier ${__explodedlast[3]} __idlast
    
    # We get the last, given the desired id based on the scope
    __candidatefromlast="v${__explodedlast[0]}.${__explodedlast[1]}.${__explodedlast[2]}"
    if [[ -n "$identifier" ]]; then
      local __nextid="$identifier.1"
      if [ "$identifier" == "${__idlast[0]}" ]; then
        # We target the same identifier as the last so we increase one
        __nextid="$identifier.$(( ${__idlast[1]}+1 ))"
        __candidatefromlast="$__candidatefromlast-$__nextid"
      else
        # Different identifiers, we make sure we are assigning a higher identifier, if not, we increase the version
        __candidatefromlast="$__candidatefromlast-$__nextid"
        local __comparedwithlast
        compare_versions $__candidatefromlast $lastversion __comparedwithlast
        if [ "$__comparedwithlast" == -1 ]; then
          get_next_version $__candidatefromlast $scope __candidatefromlast
          __candidatefromlast="$__candidatefromlast-$__nextid"
        fi
      fi
    fi
  fi

  # Then we try to get the version based on the latest final one
  local __candidatefromfinal=$FIRST_VERSION
  get_next_version $finalversion $scope __candidatefromfinal
  if [[ -n "$identifier" ]]; then
    __candidatefromfinal="$__candidatefromfinal-$identifier.1"
  fi

  # Finally we compare both candidates
  local __resultversion
  local __result
  compare_versions $__candidatefromlast $__candidatefromfinal __result
  case $__result in
    0)
      __resultversion=$__candidatefromlast
      ;;
    -1)
      __resultversion="$__candidatefromfinal"
      ;;
    1)
      __resultversion=$__candidatefromlast
      ;;
  esac

  eval "$1=$__resultversion"
}

function increase_version {
  local __version=

  if [ -z $forcedversion ]; then
    bump_version __version
  else
    if [[ $forcedversion =~ $SEMVER_REGEX ]] ; then
      compare_versions $forcedversion $lastversion __result
      if [ $__result -le 0 ]; then
        echo "Version can't be lower than last version: $lastversion"
        exit 1
      fi
    else
      echo "Non valid version to bump"
      exit 1
    fi
    __version=$forcedversion
  fi

  if [ "$displayonly" == "true" ]; then
    echo "$__version"
  else
    if [ "$forcetag" == "false" ]; then
      check_git_dirty_status
    fi
    local __commitlist
    if [ "$finalversion" == "$FIRST_VERSION" ] || [ "$hasversiontag" != "true" ]; then
      __commitlist="$(git log --pretty=oneline | cat)"
    else
      __commitlist="$(git log --pretty=oneline $finalversion... | cat)"
    fi

    # If we are forcing a bump, we add bump to the commit list
    if [[ -z $__commitlist && "$forcetag" == "true" ]]; then
      __commitlist="bump"
    fi

    if [[ -z $__commitlist ]]; then
      echo "No commits since the last final version, not bumping version"
    else
      if [[ -z $versionname ]]; then
        versionname=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
      fi
      local __message="$versionname
$__commitlist"

      # We check we have info on the user
      local __username=$(git config user.name)
      if [ -z "$__username" ]; then
        __username=$(id -u -n)
        git config user.name $__username
      fi
      local __useremail=$(git config user.email)
      if [ -z "$__useremail" ]; then
        __useremail=$(hostname)
        git config user.email "$__username@$__useremail"
      fi

      git tag -a $__version -m "$__message" 

      # If we have a remote, we push there
      local __remote=${SEMTAG_REMOTE:-$(git remote)}
      if [[ -n $__remote ]]; then
        git push $__remote $__version > /dev/null
        if [ $? -eq 0 ]; then
          echo "$__version"
        else
          echo "Error pushing the tag $__version to $__remote"
          exit 1
        fi
      else
        echo "$__version"
      fi
    fi
  fi
}

function check_git_dirty_status {
  local __repostatus=
  get_work_tree_status __repostatus

  if [ "$__repostatus" == "uncommitted" ]; then
    echo "ERROR: You have uncommitted changes"
    git status --porcelain
    exit 1
  fi

  if [ "$__repostatus" == "unstaged" ]; then
    echo "ERROR: You have unstaged changes"
    git status --porcelain
    exit 1
  fi
}

# Get the total amount of lines of code in the repo
function get_total_lines {
  local __empty_id="$(git hash-object -t tree /dev/null)"
  local __changes="$(git diff --numstat $__empty_id | cat)"
  local __added_deleted=$1
  get_changed_lines "$__changes" $__added_deleted
}

# Get the total amount of lines of code since the provided tag
function get_sincetag_lines {
  local __sincetag=$1
  local __changes="$(git diff --numstat $__sincetag | cat)"
  local __added_deleted=$2
  get_changed_lines "$__changes" $__added_deleted
}

function get_changed_lines {
  local __changes_numstat=$1
  local __result=$2
  IFS=$'\n' read -rd '' -a __changes_array <<<"$__changes_numstat"
  local __diff_regex="^([0-9]+)[[:space:]]+([0-9]+)[[:space:]]+.+$"

  local __total_added=0
  local __total_deleted=0
  for i in "${__changes_array[@]}"
  do
    if [[ $i =~ $__diff_regex ]] ; then
      local __added=${BASH_REMATCH[1]}
      local __deleted=${BASH_REMATCH[2]}
      __total_added=$(( $__total_added+$__added ))
      __total_deleted=$(( $__total_deleted+$__deleted ))
    fi
  done
  eval "$2=( $__total_added $__total_deleted )"
}

function get_scope_auto {
  local __verbose=$2
  local __total=0
  local __since=0
  local __scope=

  get_total_lines __total
  get_sincetag_lines $finalversion __since

  local __percentage=0
  if [ "$__total" != "0" ]; then
    local __percentage=$(( 100*$__since/$__total ))
    if [ $__percentage -gt "10" ]; then
      __scope="minor"
    else
      __scope="patch"
    fi
  fi

  eval "$1=$__scope"
  if [[ -n "$__verbose" ]]; then
    echo "[Auto Scope] Percentage of lines changed: $__percentage"
    echo "[Auto Scope] : $__scope"
  fi
}

function get_work_tree_status {
  # Update the index
  git update-index -q --ignore-submodules --refresh > /dev/null
  eval "$1="

  if ! git diff-files --quiet --ignore-submodules -- > /dev/null
  then
    eval "$1=unstaged"
  fi

  if ! git diff-index --cached --quiet HEAD --ignore-submodules -- > /dev/null
  then
    eval "$1=uncommitted"
  fi
}

function get_current {
  if [ "$hasversiontag" == "true" ]; then
    local __commitcount="$(git rev-list $lastversion.. --count)"
  else
    local __commitcount="$(git rev-list --count HEAD)"
  fi
  local __status=
  get_work_tree_status __status
  
  if [ "$__commitcount" == "0" ] && [ -z "$__status" ]; then
    eval "$1=$lastversion"
  else
    local __buildinfo="$(git rev-parse --short HEAD)"
    local __currentbranch="$(git rev-parse --abbrev-ref HEAD)"
    if [ "$__currentbranch" != "master" ]; then
      __buildinfo="$__currentbranch.$__buildinfo"
    fi

    local __suffix=
    if [ "$__commitcount" != "0" ]; then
      if [ -n "$__suffix" ]; then
        __suffix="$__suffix."
      fi
      __suffix="$__suffix$__commitcount"
    fi
    if [ -n "$__status" ]; then
      if [ -n "$__suffix" ]; then
        __suffix="$__suffix."
      fi
      __suffix="$__suffix$__status"
    fi

    __suffix="$__suffix+$__buildinfo"
    if [ "$lastversion" == "$finalversion" ]; then
      scope="patch"
      identifier=
      local __bumped=
      bump_version __bumped
      eval "$1=$__bumped-dev.$__suffix"
    else
      eval "$1=$lastversion.$__suffix"
    fi
  fi
}

function init {
  git fetch > /dev/null
  TAGS="$(git tag)"
  IFS=$'\n' read -rd '' -a TAG_ARRAY <<<"$TAGS"

  get_latest ${TAG_ARRAY[@]}
  currentbranch="$(git rev-parse --abbrev-ref HEAD)"
}

case $ACTION in
  --help)
    echo -e "$HELP"
    ;;
  --version)
    echo -e "${PROG}: $PROG_VERSION"
    ;;
  final)
    init
    diff=$(git diff master | cat)
    if [ "$forcetag" == "false" ]; then
      if [ -n "$diff" ]; then
        echo "ERROR: Branch must be updated with master for final versions"
        exit 1
      fi
    fi
    increase_version
    ;;
  alpha|beta)
    init
    identifier="$ACTION"
    increase_version
    ;;
  candidate)
    init
    identifier="rc"
    increase_version
    ;;
  getlast)
    init
    echo "$lastversion"
    ;;
  getfinal)
    init
    echo "$finalversion"
    ;;
  getcurrent)
    init
    get_current current
    echo "$current"
    ;;
  get)
    init
    echo "Current final version: $finalversion"
    echo "Last tagged version:   $lastversion"
    ;;
  *)
    echo "'$ACTION' is not a valid command, see --help for available commands."
    ;;
esac