#!/usr/bin/env bash
# Merge brain settings-fragment.json into consumer's settings.json
# Replaces: enabledPlugins, permissions, hooks
# Preserves: theme, editorMode, statusLine, all other keys
#
# Usage: merge-settings.sh <consumer-settings.json> <brain-fragment.json>
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
source "$SCRIPT_DIR/common.sh"

target="$1"
fragment="$2"

require_cmd jq || exit 1
[ -f "$fragment" ] || { log_error "Fragment not found: $fragment"; exit 1; }

# If target doesn't exist, just copy fragment
if [ ! -f "$target" ]; then
    log_info "Target settings.json missing, creating from fragment"
    cp "$fragment" "$target"
    exit 0
fi

# Backup
backup="${target}.bak.$(date +%s)"
cp "$target" "$backup"

# Merge: target.* keys preserved EXCEPT enabledPlugins/permissions/hooks — those are REPLACED
# (not deep-merged) from fragment. Use --slurpfile to load fragment into $frag.
tmp="${target}.tmp"
jq --slurpfile frag "$fragment" \
   '.enabledPlugins = $frag[0].enabledPlugins
    | .permissions  = $frag[0].permissions
    | .hooks        = $frag[0].hooks' \
    "$target" > "$tmp"

# Validate output JSON
jq empty "$tmp" || { log_error "Merge produced invalid JSON"; rm "$tmp"; exit 1; }

mv "$tmp" "$target"
log_info "settings.json merged (backup: $backup)"