#!/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"
}

# ─── Target-Prefix Migration (used by `rename`) ────────────────────
# Generic helpers over the whole "<target_name>/" directory on the state
# branch — agnostic to which command wrote the individual files inside it
# (this file's per-branch state, or onboard.sh's onboard.json/adopt.json).

# List every path under <target_name>/ on the freshly-fetched state branch.
# One relative path per line (e.g. "billing/main.json"); empty if none —
# including when the state branch doesn't exist yet at all.
state_list_target_files() {
  local target_name="$1"
  git fetch origin "$STATE_BRANCH" 2>/dev/null || true
  git rev-parse -q --verify "origin/${STATE_BRANCH}" >/dev/null 2>&1 || return 0
  git ls-tree -r --name-only "origin/${STATE_BRANCH}" -- "${target_name}/" 2>/dev/null
}

# Move every file under <old_name>/ to <new_name>/ (basename preserved), and
# — when new_filter is non-empty — force `.last_forward.josh_filter` to
# new_filter in each moved JSON file that has that key (whatever value it
# currently holds; we don't need to know the prior value, which keeps this
# safe to re-run mid-rename after the config has already been edited).
# Files without that key (e.g. onboard.json) pass through untouched. Both
# the move and the content rewrite land in ONE commit + push.
#
# No-op (returns 0, no commit) if <old_name>/ has no files.
# Dies before mutating anything if any destination path already exists.
#
# Usage: state_migrate_target_prefix <old_name> <new_name> [new_filter]
state_migrate_target_prefix() {
  local old_name="$1" new_name="$2" new_filter="${3:-}"
  local files
  files=$(state_list_target_files "$old_name")
  [ -n "$files" ] || return 0

  local tmp_dir
  tmp_dir=$(mktemp -d)
  git worktree add "$tmp_dir" "origin/${STATE_BRANCH}" 2>/dev/null \
    || { rm -rf "$tmp_dir"; die "Failed to check out ${STATE_BRANCH}"; }

  # The migration itself runs in a subshell so a mid-flight `exit` (from a
  # collision `die`, or any unexpected failure) can't skip the worktree
  # cleanup below. Its exit status is captured explicitly and re-raised via
  # an unconditional `exit` — relying on the caller's `set -e` to propagate a
  # failure out of a subshell is NOT reliable (e.g. bats' `run` disables
  # errexit while capturing output), so this must not depend on it.
  local migrate_status=0
  (
    cd "$tmp_dir" || exit 1
    local f base dest

    # Pre-flight collision check across all files before mutating anything.
    while IFS= read -r f; do
      [ -n "$f" ] || continue
      base="${f#"${old_name}"/}"
      dest="${new_name}/${base}"
      if [ "$f" != "$dest" ] && [ -e "$dest" ]; then
        die "Destination '${dest}' already exists on ${STATE_BRANCH} — refusing to overwrite"
      fi
    done <<< "$files"

    while IFS= read -r f; do
      [ -n "$f" ] || continue
      base="${f#"${old_name}"/}"
      dest="${new_name}/${base}"
      if [ "$f" != "$dest" ]; then
        mkdir -p "$(dirname "$dest")"
        git mv "$f" "$dest"
      fi
      if [ -n "$new_filter" ]; then
        jq --arg new "$new_filter" \
          'if has("last_forward") and (.last_forward | has("josh_filter")) then .last_forward.josh_filter = $new else . end' \
          "$dest" > "${dest}.tmp" && mv "${dest}.tmp" "$dest"
        git add "$dest"
      fi
    done <<< "$files"

    if ! git diff --cached --quiet 2>/dev/null; then
      git -c user.name="$BOT_NAME" -c user.email="$BOT_EMAIL" \
        commit -m "state: rename ${old_name} -> ${new_name}"
      git push origin "HEAD:${STATE_BRANCH}" \
        || die "Failed to push state migration for ${old_name} -> ${new_name}"
    fi
  ) || migrate_status=$?
  git worktree remove "$tmp_dir" 2>/dev/null || rm -rf "$tmp_dir"
  [ "$migrate_status" -eq 0 ] || exit "$E_GENERAL"
}