#!/usr/bin/env bash

set -e

if [[ $# -lt 2 ]]; then
    echo "Usage: $0 <params.ini> <template> [--output <output_file>]"
    exit 1
fi

PARAMS_FILE="$1"
TEMPLATE_FILE="$2"
OUTPUT_FILE="${TEMPLATE_FILE}.out"

# Optional --output <filename>
if [[ "$3" == "--output" && -n "$4" ]]; then
    OUTPUT_FILE="$4"
fi

declare -A PARAMS

# Load params.ini (ignore [section] headers)
while IFS='=' read -r key value; do
    # Trim whitespace and ignore comments/sections
    key="${key%%\#*}"   # remove inline comments
    value="${value%%\#*}"
    key="$(echo "$key" | xargs)"     # trim leading/trailing whitespace
    value="$(echo "$value" | xargs)"
    [[ -z "$key" || "$key" =~ ^\[.*\]$ ]] && continue

    key_upper=$(echo "$key" | tr '[:lower:]' '[:upper:]')
    PARAMS["$key_upper"]="$value"
done < "$PARAMS_FILE"

# Read template into a variable
template=$(<"$TEMPLATE_FILE")

# Replace placeholders (only when surrounded by spaces)
for key in "${!PARAMS[@]}"; do
    val="${PARAMS[$key]}"
    # Use sed to do space-surrounded substitution
    template=$(echo "$template" | sed -E "s/([[:space:]])$key([[:space:]])/$val/g")
done

# Save to output file
echo "$template" > "$OUTPUT_FILE"
echo "Wrote output to $OUTPUT_FILE"