Documenting base ruleset drift

[ajhalme]

Made a script for applying changes in saved game unitPrototype to the matching base ruleset field.

This draft PR is not intended to be merged as is, just a way to document "drift" between what the save files are given and what the base ruleset provides. The diff/drift here is based on latest Development branch as of this writing.

Issues

Notable issues when reading a Civ3 save in OC3, saving the game in standard OC3 json save file format, and then applying unitPrototype on top of the OC3 base ruleset:

• Unique units replacing upgradeTo paths
• flag placement (rotateBeforeAttack): the field order in code doesn't match current ruleset order, resulting in this add/remove noise
• blank producibleBy getting removed
• Unicode encoding of city names, etc.
• Whitespace

[ajhalme]

The ruleset-save patch/compare script below. (note -n flag for a dry-run)

I run it like so:

./merge.sh <OpenCiv>/C7/Lua/game_modes/base-ruleset.json <Civ3>/Conquests/Saves/curragh5.SAV.json

#!/usr/bin/bash

# Usage: ./merge.sh [-n] <A.json> <B.json>
# -n  Dry run: show diff without modifying A.json

DRY_RUN=false

if [ "$1" = "-n" ]; then
    DRY_RUN=true
    shift
fi

if [ $# -ne 2 ]; then
    echo "Usage: $0 [-n] <target.json> <source.json>"
    exit 1
fi

A="$1"
B="$2"
UPDATED="${A%.json}_updated.json"

if [ ! -f "$A" ]; then
    echo "Error: '$A' not found"
    exit 1
fi

if [ ! -f "$B" ]; then
    echo "Error: '$B' not found"
    exit 1
fi

jq --slurpfile b "$B" '.unitPrototypes = $b[0].unitPrototypes' "$A" > "$UPDATED"

if [ "$DRY_RUN" = true ]; then
    echo "Dry run — diff of '$A' vs proposed changes:"
    diff "$A" "$UPDATED"
    rm "$UPDATED"
else
    mv "$UPDATED" "$A"
    echo "Done"
fi