#!/usr/bin/env bash
# lib/state.sh — Sync state management on orphan branch
#
# State persists on an orphan git branch (default: josh-sync-state),
# committed and pushed to origin. Survives CI runner teardown.
#
# Storage layout:
#   origin/josh-sync-state/
#     <target>/<branch>.json    (e.g., billing/main.json)
#
# JSON per state file:
#   {
#     "last_forward": { "mono_sha": "...", "subrepo_sha": "...", "timestamp": "...", "status": "..." },
#     "last_reverse": { "subrepo_sha": "...", "mono_sha": "...", "timestamp": "...", "status": "..." }
#   }
#
# Forward and reverse state are independent — updated with jq merge.
#
# Requires: lib/core.sh sourced first
# Expects: JOSH_SYNC_TARGET_NAME, BOT_NAME, BOT_EMAIL (set by load_target)

STATE_BRANCH="${JOSH_SYNC_STATE_BRANCH:-josh-sync-state}"

# ─── State Key ──────────────────────────────────────────────────────
# Namespace with target: "billing" + "main" → "billing/main"
# Slashes in branch names converted to hyphens.

state_key() {
  local branch_key="${1//\//-}"
  echo "${JOSH_SYNC_TARGET_NAME}/${branch_key}"
}

# ─── Read State ─────────────────────────────────────────────────────

read_state() {
  local key
  key=$(state_key "$1")
  git fetch origin "$STATE_BRANCH" 2>/dev/null || true
  git show "origin/${STATE_BRANCH}:${key}.json" 2>/dev/null || echo '{}'
}

# ─── Write State ────────────────────────────────────────────────────
# Uses git worktree to avoid touching the working tree.

write_state() {
  local key
  key=$(state_key "$1")
  local state_json="$2"
  local tmp_dir
  tmp_dir=$(mktemp -d)

  # Try to check out existing state branch, or create orphan
  if git rev-parse "origin/${STATE_BRANCH}" >/dev/null 2>&1; then
    git worktree add "$tmp_dir" "origin/${STATE_BRANCH}" 2>/dev/null
  else
    git worktree add --detach "$tmp_dir" 2>/dev/null
    (cd "$tmp_dir" && git checkout --orphan "$STATE_BRANCH" && git rm -rf . 2>/dev/null || true)
  fi

  # Create target subdirectory and write state
  mkdir -p "$(dirname "${tmp_dir}/${key}.json")"
  echo "$state_json" | jq '.' > "${tmp_dir}/${key}.json"

  (
    cd "$tmp_dir" || exit
    git add -A
    if ! git diff --cached --quiet 2>/dev/null; then
      git -c user.name="$BOT_NAME" -c user.email="$BOT_EMAIL" \
        commit -m "state: update ${key}"
      git push origin "HEAD:${STATE_BRANCH}" || log "WARN" "Failed to push state"
    fi
  )

  git worktree remove "$tmp_dir" 2>/dev/null || rm -rf "$tmp_dir"
}