#!/bin/sh
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2026 CyberMind.FR / SecuBox
#
# RPCD backend for ZKP Hamiltonian Dashboard
# Wraps zkp_keygen, zkp_prover, zkp_verifier CLI tools

. /usr/share/libubox/jshn.sh

readonly ZKP_DIR="/var/lib/zkp"
readonly GRAPHS_DIR="$ZKP_DIR/graphs"
readonly KEYS_DIR="$ZKP_DIR/keys"
readonly PROOFS_DIR="$ZKP_DIR/proofs"

# Ensure directories exist
init_dirs() {
	mkdir -p "$GRAPHS_DIR" "$KEYS_DIR" "$PROOFS_DIR" 2>/dev/null
}

# Check if ZKP tools are available
check_tools() {
	command -v zkp_keygen >/dev/null 2>&1 && \
	command -v zkp_prover >/dev/null 2>&1 && \
	command -v zkp_verifier >/dev/null 2>&1
}

# Get library version
get_version() {
	if check_tools; then
		zkp_keygen --version 2>/dev/null | head -1 || echo "1.0.0"
	else
		echo "not installed"
	fi
}

# Count saved keys
count_keys() {
	init_dirs
	ls -1 "$KEYS_DIR"/*.key 2>/dev/null | wc -l
}

# ============== RPC Methods ==============

method_status() {
	local tools_ok="false"
	local version="not installed"
	local key_count=0

	if check_tools; then
		tools_ok="true"
		version=$(get_version)
	fi

	init_dirs
	key_count=$(ls -1 "$KEYS_DIR"/*.key 2>/dev/null | wc -l)

	cat <<EOF
{"tools_available":$tools_ok,"version":"$version","key_count":$key_count,"graphs_dir":"$GRAPHS_DIR","keys_dir":"$KEYS_DIR","proofs_dir":"$PROOFS_DIR"}
EOF
}

method_list_keys() {
	init_dirs

	local first=1
	echo -n '{"keys":['

	for keyfile in "$KEYS_DIR"/*.key; do
		[ -f "$keyfile" ] || continue

		local name=$(basename "$keyfile" .key)
		local graphfile="$GRAPHS_DIR/${name}.graph"
		local nodes=0
		local graph_size=0
		local key_size=0
		local created=0

		if [ -f "$graphfile" ]; then
			graph_size=$(stat -c %s "$graphfile" 2>/dev/null || echo 0)
			nodes=$(od -A n -t u1 -j 4 -N 1 "$graphfile" 2>/dev/null | tr -d ' ' || echo 0)
		fi

		key_size=$(stat -c %s "$keyfile" 2>/dev/null || echo 0)
		created=$(stat -c %Y "$keyfile" 2>/dev/null || echo 0)

		[ "$first" = "1" ] || echo -n ','
		first=0
		echo -n "{\"name\":\"$name\",\"nodes\":${nodes:-0},\"graph_size\":$graph_size,\"key_size\":$key_size,\"created\":$created}"
	done

	echo ']}'
}

method_keygen() {
	local nodes density name

	read -r input
	json_load "$input"
	json_get_var nodes nodes
	json_get_var density density
	json_get_var name name

	# Defaults
	[ -z "$nodes" ] && nodes=20
	[ -z "$density" ] && density="0.8"
	[ -z "$name" ] && name="key_$(date +%s)"

	# Validate
	if [ "$nodes" -lt 4 ] || [ "$nodes" -gt 50 ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Nodes must be between 4 and 50"
		json_dump
		return
	fi

	# Sanitize name
	name=$(echo "$name" | sed 's/[^a-zA-Z0-9_-]/_/g')

	init_dirs

	local graphfile="$GRAPHS_DIR/${name}.graph"
	local keyfile="$KEYS_DIR/${name}.key"

	# Check if already exists
	if [ -f "$keyfile" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Key '$name' already exists"
		json_dump
		return
	fi

	# Generate
	if ! check_tools; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "ZKP tools not installed"
		json_dump
		return
	fi

	# Create temp directory for generation
	local tmpdir="/tmp/zkp_gen_$$"
	mkdir -p "$tmpdir"
	local prefix="$tmpdir/$name"

	local output
	output=$(zkp_keygen -n "$nodes" -r "$density" -o "$prefix" 2>&1)
	local rc=$?

	# Move generated files to proper locations
	if [ $rc -eq 0 ] && [ -f "${prefix}.graph" ] && [ -f "${prefix}.key" ]; then
		mv "${prefix}.graph" "$graphfile"
		mv "${prefix}.key" "$keyfile"
	fi
	rm -rf "$tmpdir"

	if [ $rc -eq 0 ] && [ -f "$graphfile" ] && [ -f "$keyfile" ]; then
		local graph_size=$(stat -c %s "$graphfile")
		local key_size=$(stat -c %s "$keyfile")

		json_init
		json_add_boolean "success" 1
		json_add_string "name" "$name"
		json_add_int "nodes" "$nodes"
		json_add_string "density" "$density"
		json_add_int "graph_size" "$graph_size"
		json_add_int "key_size" "$key_size"
		json_add_string "output" "$output"
		json_dump
	else
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Keygen failed: $output"
		json_dump
	fi
}

method_prove() {
	local name

	read -r input
	json_load "$input"
	json_get_var name name

	if [ -z "$name" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Missing key name"
		json_dump
		return
	fi

	local graphfile="$GRAPHS_DIR/${name}.graph"
	local keyfile="$KEYS_DIR/${name}.key"
	local prooffile="$PROOFS_DIR/${name}.proof"

	if [ ! -f "$graphfile" ] || [ ! -f "$keyfile" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Key '$name' not found"
		json_dump
		return
	fi

	if ! check_tools; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "ZKP tools not installed"
		json_dump
		return
	fi

	local output
	output=$(zkp_prover -g "$graphfile" -k "$keyfile" -o "$prooffile" 2>&1)
	local rc=$?

	if [ $rc -eq 0 ] && [ -f "$prooffile" ]; then
		local proof_size=$(stat -c %s "$prooffile")
		# Base64 encode for transport (first 1KB for preview)
		local proof_preview=$(head -c 1024 "$prooffile" | base64 -w 0)

		json_init
		json_add_boolean "success" 1
		json_add_string "name" "$name"
		json_add_int "proof_size" "$proof_size"
		json_add_string "proof_file" "$prooffile"
		json_add_string "proof_preview" "$proof_preview"
		json_add_string "output" "$output"
		json_dump
	else
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Prove failed: $output"
		json_dump
	fi
}

method_verify() {
	local name

	read -r input
	json_load "$input"
	json_get_var name name

	if [ -z "$name" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Missing key name"
		json_dump
		return
	fi

	local graphfile="$GRAPHS_DIR/${name}.graph"
	local prooffile="$PROOFS_DIR/${name}.proof"

	if [ ! -f "$graphfile" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Graph '$name' not found"
		json_dump
		return
	fi

	if [ ! -f "$prooffile" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Proof '$name' not found (run prove first)"
		json_dump
		return
	fi

	if ! check_tools; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "ZKP tools not installed"
		json_dump
		return
	fi

	local output result
	output=$(zkp_verifier -g "$graphfile" -p "$prooffile" 2>&1)
	local rc=$?

	# Parse result from output
	if echo "$output" | grep -q "ACCEPT"; then
		result="ACCEPT"
	elif echo "$output" | grep -q "REJECT"; then
		result="REJECT"
	else
		result="UNKNOWN"
	fi

	json_init
	json_add_boolean "success" 1
	json_add_string "name" "$name"
	json_add_string "result" "$result"
	json_add_boolean "valid" "$([ "$result" = "ACCEPT" ] && echo 1 || echo 0)"
	json_add_string "output" "$output"
	json_dump
}

method_delete_key() {
	local name

	read -r input
	json_load "$input"
	json_get_var name name

	if [ -z "$name" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Missing key name"
		json_dump
		return
	fi

	local graphfile="$GRAPHS_DIR/${name}.graph"
	local keyfile="$KEYS_DIR/${name}.key"
	local prooffile="$PROOFS_DIR/${name}.proof"

	local deleted=0
	[ -f "$graphfile" ] && rm -f "$graphfile" && deleted=$((deleted + 1))
	[ -f "$keyfile" ] && rm -f "$keyfile" && deleted=$((deleted + 1))
	[ -f "$prooffile" ] && rm -f "$prooffile" && deleted=$((deleted + 1))

	json_init
	json_add_boolean "success" 1
	json_add_string "name" "$name"
	json_add_int "files_deleted" "$deleted"
	json_dump
}

method_get_graph() {
	local name

	read -r input
	json_load "$input"
	json_get_var name name

	if [ -z "$name" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Missing key name"
		json_dump
		return
	fi

	local graphfile="$GRAPHS_DIR/${name}.graph"

	if [ ! -f "$graphfile" ]; then
		json_init
		json_add_boolean "success" 0
		json_add_string "error" "Graph '$name' not found"
		json_dump
		return
	fi

	# Extract graph info from binary
	local nodes=$(od -A n -t u1 -j 4 -N 1 "$graphfile" 2>/dev/null | tr -d ' ')
	local graph_size=$(stat -c %s "$graphfile")

	# Generate simple adjacency representation
	# Read adjacency bits and create edge list
	local edges=""
	local i=0

	json_init
	json_add_boolean "success" 1
	json_add_string "name" "$name"
	json_add_int "nodes" "${nodes:-0}"
	json_add_int "size" "$graph_size"
	json_add_string "file" "$graphfile"
	json_dump
}

# ============== Main Dispatcher ==============

case "$1" in
	list)
		echo '{'
		echo '"status":{},'
		echo '"list_keys":{},'
		echo '"get_graph":{"name":"String"},'
		echo '"keygen":{"nodes":"Number","density":"String","name":"String"},'
		echo '"prove":{"name":"String"},'
		echo '"verify":{"name":"String"},'
		echo '"delete_key":{"name":"String"}'
		echo '}'
		;;
	call)
		case "$2" in
			status)     method_status ;;
			list_keys)  method_list_keys ;;
			get_graph)  method_get_graph ;;
			keygen)     method_keygen ;;
			prove)      method_prove ;;
			verify)     method_verify ;;
			delete_key) method_delete_key ;;
			*)
				json_init
				json_add_boolean "success" 0
				json_add_string "error" "Unknown method: $2"
				json_dump
				;;
		esac
		;;
esac