#!/usr/bin/env bash
# Replay linear dev history as feature/fix branches with merge --no-ff.
# Requires: scripts/history-epic-manifest.tsv and tag backup/pre-rewrite-2026-09-13
set -euo pipefail

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
MANIFEST="${ROOT_DIR}/scripts/history-epic-manifest.tsv"
BACKUP_TAG="backup/pre-rewrite-2026-09-13"
SOURCE_BRANCH="dev"
TARGET_BRANCH="dev-rewritten"
DRY_RUN="${DRY_RUN:-0}"

declare -A MSG_OVERRIDE=(
  [d27b0ad]="docs(ops): 建立仓库基础架构、三分支规范与环境运行文档"
  [91985a2]="fix(quality): 闭环 Go 质量门禁（鉴权富化/V0.5/vet/health/KB gate/记忆轮询）"
  [546de52]="ci(qa): add QA-001 gate with go vet, short tests, and migration check."
  [e82b624]="docs(plan): add production governance plan and Phase 0 authz matrix"
  [77d3da1]="docs(plan): add Phase 1 IAM and authorization implementation plan"
  [ba249a5]="chore(scripts): fix backfill script import and run projection for ws_intake"
)

log() { echo "[rewrite] $*"; }
die() { echo "[rewrite] ERROR: $*" >&2; exit 1; }

[[ -f "${MANIFEST}" ]] || die "missing manifest: ${MANIFEST}"
git rev-parse "${BACKUP_TAG}" >/dev/null 2>&1 || die "missing backup tag ${BACKUP_TAG}"

cd "${ROOT_DIR}"

if [[ "${DRY_RUN}" == "1" ]]; then
  log "DRY_RUN=1 — manifest entries:"
  tail -n +2 "${MANIFEST}"
  exit 0
fi

current_branch="$(git branch --show-current)"
[[ "${current_branch}" == "${SOURCE_BRANCH}" ]] || die "checkout ${SOURCE_BRANCH} first (on ${current_branch})"

if git show-ref --verify --quiet "refs/heads/${TARGET_BRANCH}"; then
  die "branch ${TARGET_BRANCH} already exists; delete it before rerun"
fi

log "creating orphan branch ${TARGET_BRANCH}"
git checkout --orphan "${TARGET_BRANCH}"
git rm -rf . >/dev/null 2>&1 || true
git commit --allow-empty -m "chore: history rewrite root anchor"

commit_range() {
  local start="$1" end="$2"
  if [[ "${start}" == "${end}" ]]; then
    echo "${start}"
    return
  fi
  if git rev-parse "${start}^" >/dev/null 2>&1; then
    git rev-list --reverse "${start}^..${end}"
  else
    echo "${start}"
    git rev-list --reverse "${start}..${end}"
  fi
}

cherry_pick_commit() {
  local hash="$1"
  if ! git cherry-pick "${hash}"; then
    die "cherry-pick failed at ${hash}; run git cherry-pick --abort and fix manifest/script"
  fi
  if [[ -n "${MSG_OVERRIDE[${hash}]+x}" ]]; then
    git commit --amend -m "${MSG_OVERRIDE[${hash}]}"
  fi
}

cherry_pick_range() {
  local start="$1" end="$2"
  local hash
  while read -r hash; do
    [[ -n "${hash}" ]] || continue
    log "  cherry-pick ${hash}"
    cherry_pick_commit "${hash}"
  done < <(commit_range "${start}" "${end}")
}

while IFS=$'\t' read -r slug branch_type start end merge_msg; do
  branch="${branch_type}/${slug}"
  log "epic ${slug}: ${branch} (${start}..${end})"

  git checkout -b "${branch}" "${TARGET_BRANCH}"
  cherry_pick_range "${start}" "${end}"

  git checkout "${TARGET_BRANCH}"
  git merge --no-ff "${branch}" -m "${merge_msg}"
  git branch -d "${branch}"
done < <(tail -n +2 "${MANIFEST}")

log "verifying tree matches ${BACKUP_TAG}"
if ! git diff --quiet "${BACKUP_TAG}" HEAD; then
  die "tree mismatch after rewrite — aborting before branch swap"
fi

log "replacing ${SOURCE_BRANCH} with rewritten history"
git branch -m "${SOURCE_BRANCH}" "${SOURCE_BRANCH}-old-linear"
git branch -m "${TARGET_BRANCH}" "${SOURCE_BRANCH}"

log "done. old linear history preserved on ${SOURCE_BRANCH}-old-linear"
log "verify: git diff ${BACKUP_TAG} ${SOURCE_BRANCH}  (should be empty)"