#!/bin/bash

set -euo pipefail

root_dir="$(readlink -f "$(dirname "$0")/..")"
readonly root_dir
readonly nightly_config="${SCST_NIGHTLY_CONFIG:-${root_dir}/nightly/conf/nightly.conf}"
readonly github_config="${SCST_GITHUB_MATRIX_CONFIG:-${root_dir}/.github/kernel-matrix.conf}"

# shellcheck source=../nightly/conf/nightly.conf
source "${nightly_config}"
# shellcheck source=../.github/kernel-matrix.conf
source "${github_config}"

: "${ABT_KERNELS:?ABT_KERNELS is not defined in ${nightly_config}}"
: "${GITHUB_REGRESSION_KERNEL_SELECTORS:?GITHUB_REGRESSION_KERNEL_SELECTORS is not defined in ${github_config}}"
: "${GITHUB_RPM_TARGETS:?GITHUB_RPM_TARGETS is not defined in ${github_config}}"
command -v jq >/dev/null 2>&1 || {
	echo "Error: jq is required." >&2
	exit 1
}

read -r -a raw_kernel_entries <<<"${ABT_KERNELS}"

strip_kernel_options() {
	stripped_kernel="$1"

	while true; do
		case "${stripped_kernel}" in
			*-nc) stripped_kernel="${stripped_kernel%-nc}" ;;
			*-ns) stripped_kernel="${stripped_kernel%-ns}" ;;
			*-nm) stripped_kernel="${stripped_kernel%-nm}" ;;
			*-4) stripped_kernel="${stripped_kernel%-4}" ;;
			*-f) stripped_kernel="${stripped_kernel%-f}" ;;
			*-i) stripped_kernel="${stripped_kernel%-i}" ;;
			*-u) stripped_kernel="${stripped_kernel%-u}" ;;
			*-p) stripped_kernel="${stripped_kernel%-p}" ;;
			*) return ;;
		esac
	done
}

canonical_kernel_entries=()
for raw_kernel in "${raw_kernel_entries[@]}"; do
	strip_kernel_options "${raw_kernel}"
	IFS='^' read -r -a kernel_parts <<<"${stripped_kernel}"
	if [[ ${#kernel_parts[@]} -ne 1 && ${#kernel_parts[@]} -ne 3 ]]; then
		echo "Error: invalid ABT_KERNELS entry: ${raw_kernel}" >&2
		exit 1
	fi
	canonical_kernel_entries+=("${stripped_kernel}")
done
readonly -a canonical_kernel_entries

version_matches_series() {
	local version="$1"
	local series="$2"

	[[ "${version}" == "${series}" ||
	   "${version}" == "${series}."* ||
	   "${version}" == "${series}-"* ]]
}

resolve_kernel() {
	local selector="$1"
	local entry version distro release
	local -a selector_parts entry_parts matches=()

	IFS='^' read -r -a selector_parts <<<"${selector}"
	if [[ ${#selector_parts[@]} -lt 1 || ${#selector_parts[@]} -gt 3 ]]; then
		echo "Error: invalid kernel selector: ${selector}" >&2
		return 1
	fi

	for entry in "${canonical_kernel_entries[@]}"; do
		IFS='^' read -r -a entry_parts <<<"${entry}"
		version="${entry_parts[0]}"
		distro="${entry_parts[1]:-}"
		release="${entry_parts[2]:-}"

		if [[ ${#selector_parts[@]} -eq 1 ]]; then
			if [[ -z "${distro}" ]] &&
			   version_matches_series "${version}" "${selector_parts[0]}"; then
				matches+=("${entry}")
			fi
		elif [[ "${distro}" == "${selector_parts[0]}" &&
		        "${release}" == "${selector_parts[1]}" ]]; then
			if [[ ${#selector_parts[@]} -eq 2 ]] ||
			   version_matches_series "${version}" "${selector_parts[2]}"; then
				matches+=("${entry}")
			fi
		fi
	done

	if [[ ${#matches[@]} -ne 1 ]]; then
		echo "Error: selector ${selector} matched ${#matches[@]} ABT_KERNELS entries." >&2
		return 1
	fi
	resolved_kernel="${matches[0]}"
}

emit_regression_matrix() {
	local selector kernel
	local -a versions=()
	local -A seen_selectors=()

	for selector in ${GITHUB_REGRESSION_KERNEL_SELECTORS}; do
		if [[ -n "${seen_selectors[${selector}]+present}" ]]; then
			echo "Error: duplicate regression selector: ${selector}" >&2
			return 1
		fi
		seen_selectors["${selector}"]=1
		resolve_kernel "${selector}" || return 1
		kernel="${resolved_kernel}"
		versions+=("${kernel}")
	done

	printf '%s\n' "${versions[@]}" |
		jq -Rsc 'split("\n") | map(select(length > 0)) | {version: .}'
}

emit_rpm_matrix() {
	local line target selector name base_image kernel_package kernel_repository extra
	local kernel kernel_version row
	local -a rows=()
	local -A seen_targets=() seen_selectors=()

	while IFS= read -r line; do
		[[ -n "${line}" ]] || continue
		IFS='|' read -r target selector name base_image kernel_package \
			kernel_repository extra <<<"${line}"
		if [[ -z "${target}" || -z "${selector}" || -z "${name}" ||
		      -z "${base_image}" || -z "${kernel_package}" || -n "${extra:-}" ]]; then
			echo "Error: invalid RPM target: ${line}" >&2
			return 1
		fi
		if [[ -n "${seen_targets[${target}]+present}" ]]; then
			echo "Error: duplicate RPM target: ${target}" >&2
			return 1
		fi
		if [[ -n "${seen_selectors[${selector}]+present}" ]]; then
			echo "Error: duplicate RPM selector: ${selector}" >&2
			return 1
		fi
		seen_targets["${target}"]=1
		seen_selectors["${selector}"]=1

		resolve_kernel "${selector}" || return 1
		kernel="${resolved_kernel}"
		kernel_version="${kernel%%^*}"
		row="$(
			jq -cn \
				--arg name "${name}" \
				--arg target "${target}" \
				--arg base_image "${base_image}" \
				--arg kernel_package "${kernel_package}" \
				--arg kernel_version "${kernel_version}" \
				--arg kernel_repository "${kernel_repository}" \
				'{name: $name, target: $target, base_image: $base_image,
				  kernel_package: $kernel_package,
				  kernel_version: $kernel_version,
				  kernel_repository: $kernel_repository}'
		)" || return 1
		rows+=("${row}")
	done <<<"${GITHUB_RPM_TARGETS}"

	printf '%s\n' "${rows[@]}" | jq -cs '{include: .}'
}

emit_rpm_field() {
	local target="$1"
	local field="$2"
	local matrix

	case "${field}" in
		name|base_image|kernel_package|kernel_version|kernel_repository)
			;;
		*)
		echo "Error: unsupported RPM matrix field: ${field}" >&2
		return 1
		;;
	esac

	matrix="$(emit_rpm_matrix)" || return 1
	jq -er \
		--arg target "${target}" \
		--arg field "${field}" '
		[.include[] | select(.target == $target)] |
		if length == 1 then .[0][$field]
		else error("RPM target \($target) matched \(length) entries") end
	' <<<"${matrix}"
}

case "${1:-}" in
	regression) emit_regression_matrix ;;
	rpm) emit_rpm_matrix ;;
	rpm-field)
		if [[ $# -ne 3 ]]; then
			echo "Usage: $0 rpm-field <target> <field>" >&2
			exit 2
		fi
		emit_rpm_field "$2" "$3"
		;;
	*)
		echo "Usage: $0 {regression|rpm|rpm-field}" >&2
		exit 2
		;;
esac