#!/bin/bash

declare -a PARAM_KEYS=()

trim_whitespace() {
    local s="\${1-}"
    s="\${s#"\${s%%[![:space:]]*}"}"
    s="\${s%"\${s##*[![:space:]]}"}"
    printf "%s" "\$s"
}

clear_params() {
    local key
    for key in "\${PARAM_KEYS[@]-}"; do
        unset "PARAM_\${key}"
    done
    PARAM_KEYS=()
}

validate_param_key() {
    local key="\${1-}"
    [[ "\$key" =~ ^[A-Za-z_][A-Za-z0-9_]*\$ ]]
}

validate_case_no() {
    local case_no="\${1-}"

    if [[ ! "\$case_no" =~ ^[0-9]{4}\$ ]] || [ "\$case_no" -lt 1000 ] || [ "\$case_no" -gt 9999 ]; then
        echo "ERROR: CaseNo must be a 4-digit integer in [1000, 9999], got: \${case_no:-<empty>}" >&2
        return 1
    fi
}

parse_param_file() {
    local file="\${1-}"
    local line key value

    if [ -z "\$file" ] || [ ! -f "\$file" ]; then
        echo "ERROR: Parameter file not found: \$file" >&2
        return 1
    fi

    clear_params

    while IFS= read -r line || [ -n "\$line" ]; do
        line="\${line%%#*}"
        line="\$(trim_whitespace "\$line")"
        [ -z "\$line" ] && continue
        [[ "\$line" != *"="* ]] && continue

        key="\$(trim_whitespace "\${line%%=*}")"
        value="\$(trim_whitespace "\${line#*=}")"

        [ -z "\$key" ] && continue
        if ! validate_param_key "\$key"; then
            echo "WARNING: Invalid key '\$key' in \$file, skipping" >&2
            continue
        fi

        PARAM_KEYS+=("\$key")
        printf -v "PARAM_\${key}" "%s" "\$value"
    done < "\$file"
}

get_param() {
    local key="\${1-}"
    local var="PARAM_\${key}"
    printf "%s" "\${!var-}"
}

get_param_value() {
    local file="\${1-}"
    local key="\${2-}"

    parse_param_file "\$file" || return 1
    get_param "\$key"
}

require_params() {
    local file="\${1-}"
    shift

    parse_param_file "\$file" || return 1

    local key
    local missing=0
    for key in "\$@"; do
        if [ -z "\$(get_param "\$key")" ]; then
            echo "ERROR: Required parameter '\$key' missing in \$file" >&2
            missing=1
        fi
    done

    [ "\$missing" -eq 0 ]
}

set_param_in_file() {
    local file="\${1-}"
    local key="\${2-}"
    local value="\${3-}"
    local tmp_file

    if [ -z "\$file" ] || [ ! -f "\$file" ]; then
        echo "ERROR: Parameter file not found: \$file" >&2
        return 1
    fi

    if ! validate_param_key "\$key"; then
        echo "ERROR: Invalid parameter key: \$key" >&2
        return 1
    fi

    tmp_file="\$(mktemp "\${TMPDIR:-/tmp}/params.XXXXXX")"

    awk -v key="\$key" -v value="\$value" '
        BEGIN {
            updated = 0;
            pattern = "^[[:space:]]*" key "[[:space:]]*=";
        }
        {
            if (!updated && \$0 !~ /^[[:space:]]*#/ && \$0 ~ pattern) {
                print key "=" value;
                updated = 1;
                next;
            }
            print;
        }
        END {
            if (!updated) {
                print key "=" value;
            }
        }
    ' "\$file" > "\$tmp_file"

    mv "\$tmp_file" "\$file"
}