#!/usr/bin/gawk -f

function evaluate (str) {

    for (j = 1; j <= length(str); j++) {

        if (substr(str, j, l_delimiters_begin) == var_delimiters_begin) {

            replacement = true

            k = ""

            j += l_delimiters_begin - 1

            continue

        }

        if (substr(str, j, l_delimiters_end) == var_delimiters_end) {

            replacement = false

            str = gensub(var_delimiters_begin k var_delimiters_end, conf[name][apply_case_sensivity(k)], "g", str)

            j -= l_delimiters_end k

            continue

        }

        if (replacement)

            k = k substr(str, j, 1)

    }

    return dq gensub(dq, "\\\\" dq, "g", str) dq

}

function apply_case_sensivity (str) {

    if (case_sensitive)

        return str

    else {

        if (default_case == "lower")

            return tolower(str)

        else

            return toupper(str)

    }

}

function print_version () {

    printf("%s version %s\n", appname, version)

}

function cli_error (rc) {

    print "CLI error: " rc

    exit 1

}

function help (rc) {

    line = appname "\nversion " version "\n\n\033[4mOPTIONS:\033[0m"

    while (getline < appname) {

        if (/^#help:BEGIN/) help_started = 1

        if (/^#help:END/) help_started = 0

        if (help_started) {

            if (/^[[:blank:]]*case \/\^(.+)\$\/[[:blank:]]*\:[[:blank:]]*$/) {

                option = gensub(/^[[:blank:]]*case \/\^(.+)\$\/[[:blank:]]*\:[[:blank:]]*$/, "\\1", "1")

                line = line "\n\n\033[1m" option "\033[0m"

            }

            else if (/^#help:/ && option != "") {

                split($0, helpinfo, ":")

                line = line "\n" helpinfo[2]

            }

        }

    }

    print line | "pager -R"

    exit 0

}

BEGIN {

# initialisation

    appname     = ENVIRON["_"]

    version     = "1.0.0"

    conf_arrays = ""

    filename    = ""

    sections    = ""

    dq          = "\""

    eol         = ORS

    true        = 1

    false       = 0

    clean       = false

    unset       = false

    sectionlist = false

    case_sensitive = false

    default_case = "lower"

    var_delimiters_begin = "{{{"

    var_delimiters_end   = "}}}"

    key_value_delimiter  = ""

    in_var_space_remplacement = ""

    first_element_index = 0

    for (arg = 1; arg < ARGC; arg++)

        switch (ARGV[arg]) {

#help:BEGIN

            case /^--conf=["']?.+["']?$/:

#help:file containing the configuration to read

                filename = gensub(/^--conf=["']?(.+)["']?$/, "\\1", "1", ARGV[arg])

                break

            case /^--conf$/:

#help:file containing the configuration to read

                filename = gensub(/^["']?(.+)["']?$/, "\\1", "1", ARGV[++arg])

                break

            case "--sections-list":

#help:list all sections found in given config file

                returnsectionlist = 1

                break

            case /^--section=["']?.+["']?$/:

#help:retrieve information for section <section>

                s = gensub(/^--section=["']?(.+)["']?$/, "\\1", "1", ARGV[arg])

                onlysections[s] = true

                break

#            case /^-s$/:

##help:retrieve information for section <section>

#                s = gensub(/^["']?(.+)["']?$/, "\\1", "1", ARGV[++arg])

#                onlysections[s] = true

#                break

            case /^--clean$/:

#help:output commands to clean all variables listed in configuration

                clean = true

                break

            case /^--unset$/:

#help:output commands to unset variables listed in configuration file

                unset = true

                break

            case /^--compact$/:

#help:output everything on a single line, elements seperated by semi-colon

                eol = ";"

                break

            case /^--array=["']?.+["']?$/:

#help:learns the script this entry is intented to be treated as an array, can be used multiple times for multiples array names

                arrayname=gensub(/^--array=["']?(.+)["']?$/, "\\1", "1", ARGV[arg])

                conf_arrays = conf_arrays "|" arrayname

                key_array[arrayname]++

                break

            case /^--first-element-array=[01]$/:

#help:tells the script the array index begins at 0 or 1, defaults to 0

                first_element_index = gensub(/^--first-element-array=([01])$/, "\\1", "1", ARGV[arg])

                break

            case /^--var-delim-begin=["']?.{3,}["']?$/:

#help:tells the script what is the starting chars sequence to delimitate a variable, defaults to {{{, can be -+= (for example)

                var_delimiters_begin = gensub(/^--var-delim-begin=["']?(.{3,})["']?$/, "\\1", "1", ARGV[arg])

                break

            case /^--var-delim-end=["']?.{3,}["']?$/:

#help:tells the script what is the ending chars sequence to delimitate a variable, defaults to }}}, can be =+- (for example)

                var_delimiters_end = gensub(/^--var-delim-end=["']?(.{3,})["']?$/, "\\1", "1", ARGV[arg])

                break

            case /^--case-sensitive$/:

#help:tells the script if it has to be case-sensitive, defaults to insensitive

                 case_sensitive = true

                 break

            case /^--case-insensitive(|=lower|=UPPER)$/:

#help:tells the script how to behave in insensitive mode (default)

#help: lower = variables output in lowercase (default)

#help: UPPER = variables output in UPPERCASE

                 case_sensitive = false

                 default_case = gensub(/^--case-insensitive[=]?(.*)$/, "\\1", "1", ARGV[arg])

                 if (default_case == "")

                     default_case = "lower"

                 break

            case /^--key-value-delimiter=["']?.["']?$/:

#help:tells the script which char is used to separate the key from its assorciated value in the configuration file, defaults to blank-char

                 key_value_delimiter = gensub(/^--key-value-delimiter=["']?(.)["']?$/, "\\1", "1", ARGV[arg])

                 break

            case /^--in-var-space-replacement=["']?.["']?$/:

#help:tells the script which char to use to replace a space found in a key, defaults to empty

                in_var_space_remplacement = gensub(/^--in-var-space-replacement=["']?(.)["']?$/, "\\1", "1", ARGV[arg])

                break

            case /^help$/:

#help:show this help

                 help()

                 break

            case /^version$/:

#help:show the version of the script

                 print_version()

                 exit

#help:END

            default:

                cli_error(ARGV[arg])

        }

    if (filename == "" || (getline < filename) < 0 ) exit 1

    close(filename)

    if (conf_arrays != "") {

        conf_arrays = gensub("^|", "", "1", conf_arrays)

        if (key_value_delimiter != "")

            conf_arrays = gensub(/\s/, in_var_space_remplacement, "g", conf_arrays)

        conf_arrays = apply_case_sensivity(conf_arrays)

    }

    l_delimiters_begin = length(var_delimiters_begin)

    l_delimiters_end   = length(var_delimiters_end)

    while ((getline < filename) == 1) {

        if (/^\s*(|#.*)$/)

            continue

        # section

        if (/^\s*\[.+\]\s*$/) {

            name=gensub(/^\s*\[(.+)\]\s*$/, "\\1", "g")

            for (key in key_array)

                ptr[name][key] = first_element_index

            continue

        }

        # key (delimiter) value

        else if (name != "") {

            if (key_value_delimiter != "") {

                split($0, keyvalue, "[[:blank:]]*" key_value_delimiter "[[:blank:]]*")

                key   = gensub(/\s/, in_var_space_remplacement, "g", keyvalue[1])

                value = clean ? "" : keyvalue[2] #TODO: "join" toutes les valeurs

            }

            else {

                key = $1

                value = clean ? "" : gensub("^[[:blank:]]*" $1 "[[:blank:]]*", "", "1")

            }

            key = apply_case_sensivity(key)

            if (key ~ "^(" conf_arrays ")$" && ! unset)

                conf[name][key][ptr[name][key]++] = value

            else

                conf[name][key] = value

        }

    }

    if (returnsectionlist)

        for (name in conf)

            print name

    else for (name in onlysections)

        for (key in conf[name]) {

            if (key ~ "^(" conf_arrays ")$" && ! unset)

                for (i=first_element_index; i<ptr[name][key]; i++) 

                    printf("%s[%i]=%s", key, i, evaluate(conf[name][key][i]) eol)

            else {

                if (unset)

                    printf("unset %s", key, evaluate(conf[name][key]) eol)

                else

                    printf("%s=%s", key, evaluate(conf[name][key]) eol)

            }

        }

}