#ifndef UMBRELLA_PROTO_H
#define UMBRELLA_PROTO_H

#include <stdint.h>

/*
 * Wire format: 4-byte big-endian length prefix followed by a JSON payload.
 *
 *   [uint32 length][JSON bytes...]
 *
 * All messages are JSON objects with at minimum a "cmd" or "type" field.
 *
 * Client → Daemon commands:
 *   { "cmd": "list" }
 *   { "cmd": "status", "unit": "name" }
 *   { "cmd": "attach", "unit": "name" }
 *   { "cmd": "detach" }
 *   { "cmd": "input",  "unit": "name", "data": "text\n" }
 *   { "cmd": "action", "unit": "name", "action": "update" }
 *
 * Daemon → Client responses:
 *   { "type": "ok" }
 *   { "type": "error", "message": "..." }
 *   { "type": "list",  "units": [...] }
 *   { "type": "status", "unit": "name", "state": "running", "pid": 123 }
 *   { "type": "output", "unit": "name", "data": "...", "history": true/false }
 */

#define PROTO_HDR_SIZE 4  /* bytes for the length prefix */

/*
 * proto_send: send a length-prefixed JSON message to fd.
 * json must be a null-terminated string.
 * Returns 0 on success, -1 on error.
 */
int proto_send(int fd, const char *json);

/*
 * proto_recv: receive one complete message from fd into buf.
 * buf must be PROTO_MAX_MSG bytes.
 * Returns number of bytes read (>=1), 0 on clean disconnect, -1 on error.
 */
int proto_recv(int fd, char *buf, int buf_size);

/*
 * proto_send_ok: convenience — send {"type":"ok"}
 */
int proto_send_ok(int fd);

/*
 * proto_send_error: convenience — send {"type":"error","message":"..."}
 */
int proto_send_error(int fd, const char *message);

/*
 * proto_send_output: send a chunk of console output to a client.
 * history=1 means this is buffered history, 0 means live output.
 */
int proto_send_output(int fd, const char *unit_name,
                      const char *data, int history);

/*
 * json_get_str: extract a string value from a flat JSON object.
 * Writes into out (null-terminated), up to out_size bytes.
 * Returns 1 if found, 0 if not.
 * This is a minimal parser — does not handle nested objects or arrays.
 */
int json_get_str(const char *json, const char *key, char *out, int out_size);

#endif /* UMBRELLA_PROTO_H */