#!/bin/bash


# Incremental build script.
# Main inputs are from the *.cue and *.yaml files in the top-level directory
# Assets are taken from raw/ tex/ mako/ etc and put into the output/ directory
# The output/ directory is populated with a ninja build script to do the
# actual build, along with source files that are updated for a build.
# Thus to build a full output in dir you would run: build.sh dir/ && cd dir/ && ninja build
# Once built once, a simple `ninja` in the output directory should suffice

# echo "new" | update file
# updates file with new content only if the content differs
update() {
    fname="$1"
    data="$(cat)"
    new="$(echo "$data" | sha256sum | cut -d " " -f 1)"
    old="$(sha256sum "$fname" | cut -d " " -f  1)"
    if [ "$new" != "$old" ]; then
        echo "Updating $fname"
        echo "$data" > "$fname"
    fi
}

outdir="${1:-output}/"

mkdir -p "$outdir"

json="$(cue export *.cue *.yaml)"

{
    echo "# Generated by build.sh on $(date)"

    echo "include ../rules.ninja"

EOF
} | update "$outdir/build.ninja"

# TODO: get json via `cue export *.cue *.yaml`