#!/bin/bash

set -e

E_VALIDATE="1"  # wrong password etc
E_CONFLICT="2"  # mapping already exists etc
E_INVALID="3"   # invalid argument given
E_PRIVILEGE="4" # user cannot access password etc
E_GENERAL="99"  # uncategorized error

function bootstrap {
    local fuser="$1"
    local upass="$2"
# initializes passman into a usable state, using '$1' as its initial administrator
# '$2' is the initial user's password
# returns an error if any remnants of a working state are detected, in which case it does nothing

    local count=0
    for i in user group pass
    do
        [ -e $i ] && (( count++ ))
    done

    if [ "$count" = 3 ] && [ -e group/admin.* ]
    then
        echo "passman seems to be bootstrapped already, not doing anything."
        return $E_CONFLICT

    elif [ ! "$count" = 0 ]
    then
        echo "passman seems to be in an inconsistent state, please clean up before trying to bootstrap."
        return $E_GENERAL
    fi

    mkdir user
    mkdir group
    mkdir pass
    chmod -R u=rwX,g=rX,o=rX .

    local utoken=$(make-token)
    local atoken=$(make-token)

    encrypt user/"$fuser" "$upass" "$utoken"
    encrypt group/admin."$fuser" "$utoken" "$atoken"
    encrypt user/"$fuser".admin "$atoken" "$utoken"

    return 0
}

function get-user-token {
    local uname=$1
    local pass=$2
# prints the token associated with '$1' by decrypting the file 
# user/'$1' with '$2'
# if the decryption encounters an error, its error code is returned

    decrypt user/"$uname" "$pass"
}

function get-admin-token {
    local uname="$1"
    local pass="$2"
# prints the token associated with '$1' by decrypting the file
# group/admin.'$1' with '$2'
# if the decryption encounters an error, its error code is returned

    decrypt group/admin."$uname" "$pass"
}

function encrypt {
    local name="$1"
    local pass="$2"
    local cont="$3"
# encrypts '$3' in '$1' with '$2'
# if the file exists, an error is returned
# if the encryption encounters an error, its error code is returned

    [ -e "$name" ] && return $E_CONFLICT

    touch "$name"
    chmod 600 "$name"
    echo -e "$cont" > "$name"

    export pass
    ccrypt -eq -S "" -E pass "$name" 2>/dev/null
}

function decrypt {
    local name="$1"
    local pass="$2"
# tries to decrypt and print '$1' using '$2'
# if the decryption encounters an error, its error code is returned

    export pass
    ccrypt -cq -E pass "$name" 2>/dev/null || return $E_VALIDATE
}

function make-token {
# prints a generated string for use as intermediate encryption key for groups/users

    pwgen -s 128 1
}

function list-user-groups {
    local uname="$1"
# prints all groups that '$1' belongs to as a space-delimited list

    local out=$(ls group/*.$uname 2>/dev/null | sed -r -e "s%^group/%%" -e "s%\.$uname$%%" | sort -u)
    printf "%s\n" "$out"
}

function list-group-passes {
    local gname="$1"
# prints all password files belonging to '$1' as a space-delimited list
# does not decrypt any passwords

    local out=$(ls pass/*.$gname 2>/dev/null | sed -r -e "s%^pass/%%" -e "s%\.$gname$%%" | sort -u)
    printf "%s\n" "$out"
}

function list-password-groups {
    local pname="$1"
# prints all the groups that '$1' belongs to as a space-delimited list

    local out=$(ls pass/$pname.* 2>/dev/null | sed -r "s%^pass/$pname\.%%" | sort -u)
    printf "%s\n" "$out"
}

function list-group-users {
    local gname="$1"
# prints all the users that belong to '$1' as a space-delimited list

    local out=$(ls group/$gname.* 2>/dev/null | sed -r "s%^group/$gname\.%%" | sort -u)
    printf "%s\n" "$out"
}

function list-passwords {
# prints all the passwords stored in the system
# does not decrypt any passwords, only prints identifiers
    local out=$(ls pass/ | sed -r -e "s%^pass/%%" -e "s%\.[^.]+$%%" | sort -u)
    printf "%s\n" "$out"
}

function list-users {
    local out=$(ls user/ | sed -r -e "s%^user/%%" -e "s%\.[^.]+$%%" | sort -u)
    printf "%s\n" "$out"
}

function list-groups {
    local out=$(ls group/ | sed -r -e "s%^group/%%" -e "s%\.[^.]+$%%" | sort -u)
    printf "%s\n" "$out"
}

function list-available {
    local uname="$1"
# prints all the password files that '$1' has access to as a space-delimited list
# does not decrypt any passwords

    local groups=$(list-user-groups "$uname")
    local passes=""

    for gname in $groups
    do
        passes=$(list-group-passes "$gname")' '"$passes"
    done

    local out=$(printf "%s" "$passes" | sort -u)
    printf "%s\n" "$out"
}

function show-pass {
    local uname="$1"
    local utoken="$2"
    local pname="$3"
# decrypts and prints '$3', using '$2' belonging to '$1'
# if '$1' cannot access '$3', an error is returned

    local ugroups=$(list-user-groups "$uname")
    local pgroups=$(list-password-groups "$pname")

    for group in $pgroups
    do
        echo "$ugroups" | grep -q "$group"
        if [ "$?" = "0" ]
        then
            local gtoken=$(decrypt group/"$group"."$uname" "$utoken")

            decrypt pass/"$pname"."$group" "$gtoken"
            return $?
        fi
    done
    return $E_PRIVILEGE
}

function add-user {
    local admintoken="$1"
    local uname="$2"
    local upass="$3"
# adds '$2' to the system with '$3', authenticating with '$1'
# returns an error if the username 'admin' is supplied or the username already exists
# will NOT return an error if an invalid '$1' is supplied, because there isn't necessarily anything to validate against

    local utoken=$(make-token)

    [ "$uname" = "admin" ] && return $E_CONFLICT

    encrypt user/"$uname".admin "$admintoken" "$utoken" || return $?
    encrypt user/"$uname" "$upass" "$utoken" || return $?
}

function change-user-pass {
    local utoken="$1"
    local uname="$2"
    local newpass="$3"
# changes '$2's password to '$3', authenticating with '$1'
# if the user does not belong to any groups, the password is changed without question
# otherwise, the supplied '$1' is checked against one of the groups the user belongs to

    local testfile=$(ls group/*."$uname" 2>/dev/null | tr '\n' ' ' | cut -d' ' -f1)

    [ -n "$testfile" ] && { decrypt "$testfile" "$utoken" &> /dev/null || return $E_VALIDATE; }
    rm user/"$uname"
    encrypt user/"$uname" "$newpass" "$utoken" || return $?

}

function remove-user {
    local admintoken="$1"
    local uname="$2"
# removes '$2' from the system, given that '$1' is valid
# also removes all group mappings for the user
# returns an error if the user doesn't exist or '$1' is invalid

    decrypt user/"$uname".admin "$admintoken" &> /dev/null|| return $E_VALIDATE

    rm user/"$uname"*
    rm group/*."$uname" 2>/dev/null || true
}

function make-user-admin {
    local admintoken="$1"
    local uname="$2"
# makes '$2' an administrator
# an error will be returned if '$1' is invalid

    local utoken=$(decrypt user/"$uname".admin "$admintoken") || return $E_VALIDATE

    encrypt group/admin."$uname" "$utoken" "$admintoken"
}

function unmake-user-admin {
    local admintoken="$1"
    local uname="$2"
# revokes '$2's admin privileges
# an error is returned if the user isn't an administrator or '$1' is invalid

    decrypt user/"$uname".admin "$admintoken" &> /dev/null || return $?

    rm group/admin."$uname"
}

function map-user-group {
    local admintoken="$1"
    local uname="$2"
    local gname="$3"
# adds '$2' to '$3'
# admin privileges cannot be granted via this function
# an error is returned if '$3' is 'admin', '$2' already belongs to '$3', or '$1' is invalid

    [ "$gname" = "admin" ] && return $E_PRIVILEGE
    [ -e group/"$gname"."$uname" ] && return $E_CONFLICT
    local utoken=$(decrypt user/"$uname".admin "$admintoken") || return $E_VALIDATE
    local gtoken=$(decrypt group/"$gname".admin "$admintoken") || return $E_VALIDATE

    encrypt group/"$gname"."$uname" "$utoken" "$gtoken"
}

function unmap-user-group {
    local admintoken="$1"
    local uname="$2"
    local gname="$3"
# removes '$2' from '$3'
# admin privileges cannot be revoked via this function
# an error is returned if '$3' is admin, the mapping doesn't exist, or '$1' is invalid

    [ "$gname" = "admin" ] && return $E_PRIVILEGE
    decrypt group/"$gname".admin "$admintoken" &> /dev/null || return $?

    rm group/"$gname"."$uname"
}

function add-group {
    local admintoken="$1"
    local gname="$2"
# adds a group called '$2'
# an error is returned if '$2' is 'admin', the group already exists, or '$1' is invalid

    [ "$gname" = "admin" ] && return $E_PRIVILEGE
    [ -e group/"$gname".admin ] && return $E_CONFLICT

    local gtoken=$(make-token)

    encrypt group/"$gname".admin "$admintoken" "$gtoken"
}

function remove-group {
    local admintoken="$1"
    local gname="$2"
# removes the group named '$2'
# an error is returned if '$2' is 'admin', '$2' doesn't exist, or '$1' is invalid

    [ "$gname" = "admin" ] && return $E_PRIVILEGE
    decrypt group/"$gname".admin "$admintoken" &> /dev/null || return $?

    rm pass/*."$gname" 2>/dev/null || true
    rm group/"$gname".*
}

function map-pass-group {
    local admintoken="$1"
    local pname="$2"
    local gname="$3"
# adds '$3' to '$2'
# an error is returned if '$2' is 'admin', the password is already in the group, or '$1' is invalid

    [ "$gname" = "admin" ] && return $E_PRIVILEGE
    [ -e pass/"$pname"."$gname" ] && return $E_CONFLICT

    local gtoken=$(decrypt group/"$gname".admin "$admintoken") || return $E_VALIDATE
    local pass=$(decrypt pass/"$pname".admin "$admintoken") || return $E_VALIDATE

    encrypt pass/"$pname"."$gname" "$gtoken" "$pass"
}

function unmap-pass-group {
    local admintoken="$1"
    local pname="$2"
    local gname="$3"
# removes '$3' from '$2'
# returns an error if '$2' or '$3' is 'admin', the mapping doesn't exist, or '$1' is invalid

    [ "$gname" = "admin" ] && return $E_PRIVILEGE
    decrypt pass/"$pname".admin "$admintoken" &> /dev/null || return $E_VALIDATE
    decrypt group/"$gname".admin "$admintoken" &> /dev/null || return $E_VALIDATE

    rm pass/"$pname"."$gname"
}

function add-pass {
    local admintoken="$1"
    local pname="$2"
    local pass="$3"
# adds a password to the system. It is identified by '$2', and its value is '$3'
# an error is returned if '$1' is invalid or '$2' already exists

    encrypt pass/"$pname".admin "$admintoken" "$pass"
}

function remove-pass {
    local admintoken="$1"
    local pname="$2"
# removes the password named '$2' from the system
# an error is returned if '$1' is invalid or '$2' doesn't exist

    decrypt pass/"$pname".admin "$admintoken" &> /dev/null || return $?

    rm pass/"$pname".*
}

function modify-pass {
    local admintoken="$1"
    local pname="$2"
    local newpass="$3"
# replaces the content of '$2' with '$3'
# an error is returned if '$1' is invalid or '$2' doesn't exist

    for group in $(list-password-groups "$pname")
    do
        rm pass/"$pname"."$group"
        if [ "$group" == "admin" ]
        then
            continue
        fi

        gtok=$(decrypt group/"$group".admin "$admintoken")
        res=$?
        [ -z "$gtok" ] && return "$res"

        encrypt pass/"$pname"."$group" "$gtok" "$newpass"

    done

    encrypt pass/"$pname".admin "$admintoken" "$newpass"
    return $?
}