#pragma once
/*
 * configcompare.h — cross-member active-configuration comparator
 * (config-upgrade-snapshot task 8.4, Requirement 4.2).
 *
 * Compares each cluster member's locally-held ACTIVE configuration content
 * hash, recomputed FRESH from that member's own on-disk configuration file
 * (never trusted from a cached/embedded tag), and reports whether every
 * member agrees.
 *
 * A new sibling tool to walcompare, NOT an extension of it: walcompare's
 * internal model is WAL-entry-indexed (lsn -> term, pcrc) -- an awkward fit
 * for a single (tag, sha256) value per member with no LSN dimension
 * (design.md "Regression Tooling"). Mirrors snapdiff_paths's exact
 * signature/reporting shape instead.
 *
 * Offline/file-based: no live RPC to any cluster member, consistent with
 * every other tool in this family (walcompare, snapdiff, snapverify).
 *
 * Strictly read-only: opens files O_RDONLY, mutates nothing.
 */
#include <stdint.h>
#include <stdio.h>

/* Bound on the number of members a single call can compare -- generous for
 * any real cluster size this codebase targets; a caller with more members
 * than this is almost certainly passing a malformed argument list. */
#define CONFIGCOMPARE_MAX_MEMBERS 32

typedef struct {
    int     n;                                     /* member count passed in */
    int     read_rc[CONFIGCOMPARE_MAX_MEMBERS];    /* 0 = resolved+hashed ok,
                                                     * else -errno; entries at
                                                     * or past a short-circuit
                                                     * failure are unset (0)
                                                     * and must be ignored --
                                                     * see all_present */
    uint8_t sha256[CONFIGCOMPARE_MAX_MEMBERS][32]; /* valid only where
                                                     * read_rc[i] == 0 */
    int     all_present;   /* 1 iff every member (0..n-1) was resolved and
                            * hashed successfully */
    int     all_identical; /* 1 iff all_present && every member's sha256
                            * equals the first member's */
    int     first_divergent_index; /* -1 if all_identical or !all_present;
                                    * else the first index (after the
                                    * reference, member 0) whose hash
                                    * differs from member 0's */
} configcompare_report_t;

/* Compare the active-configuration content hash of `n` members. Each
 * `conf_paths[i]` is a member's `workdir/name` directory -- the SAME
 * directory persist.c's `read_active_config_bytes()` and config_repl.c's
 * `local_config_sha256()` both resolve `conf/current` (and the versioned
 * config file it points at) under, matching where this spec's snapshot-embed
 * step also reads from. NOT the raw `conf/current` file itself -- this
 * function resolves `<path>/conf/current` and `<path>/conf/<versioned-file>`
 * internally, exactly like those two functions do.
 *
 * Prints a human-readable report to `out` (may be NULL) and fills `*rep`
 * (may be NULL). Returns:
 *   0   if every member's config was readable and all hashes are identical
 *   1   if every member's config was readable but at least one diverges
 *       (see `*rep->first_divergent_index` for which)
 *   <0  (negative errno) if `n < 2` (nothing to compare), `n` exceeds
 *       CONFIGCOMPARE_MAX_MEMBERS, or any member's config could not be
 *       resolved/read -- mirrors snapdiff_paths's early-return-on-open-
 *       failure style: the first unreadable member short-circuits the scan,
 *       and `*rep` is still filled with whatever was learned about the
 *       members checked before the failure, so the report can say which
 *       member and why. A member that could not be read is NOT evidence of
 *       matching OR mismatching configuration -- it is a distinct third
 *       outcome from "identical" and "divergent". */
int configcompare_paths(const char* const* conf_paths, int n, FILE* out,
                         configcompare_report_t* rep);