validate

#!/bin/bash
#
# Validate tablet data
#

set -e -u -o pipefail

# Execute kwalify with document on stdin, overriding file name, appropriately
# directed output and appropriate exit status.
#
# Args: filename [kwalify_arg...]
# Stdout: successful output with overriden filename
# Stderr: error output with overriden filename
#
function kwalify_strict()
{
    declare -r filename="$1";   shift
    declare output
    read -r -d '' output < <(
        kwalify "$@"
    ) || true
    if [[ $output == *[^A-Za-z]valid[^A-Za-z]* ]]; then
        printf '%s\n' "${output//(stdin)/$filename}"
        return 0
    else
        printf '%s\n' "${output//(stdin)/$filename}" >&2
        return 1
    fi
}

kwalify_strict schema.yml -m < schema.yml >/dev/null

declare passed=true
declare f
declare yaml
declare image_name
declare image_file

for f in */index.md; do
    read -r -d '' yaml < <(
        sed -ne '/^---$/,/^---$/ {/^---$/b; p}' "$f"
    ) || true

    kwalify_strict "$f" -f schema.yml <<<"$yaml" >/dev/null ||
        { passed=false; continue; }

    read -r -d '' image_name < <(
        awk '/^\s*image:\s+/ {print $2}' <<<"$yaml"
    ) || true

    if [ -z "$image_name" ]; then
        printf "%s: image is not specified\\n" "$f" >&2
        passed=false
        continue
    fi
    image_file="${f%index.md}/${image_name}.jpg"
    if ! [ -e "$image_file" ]; then
        printf "%s: image doesn't exist: %s\\n" "$f" "$image_file" >&2
        passed=false
    fi
done

"$passed"