#!/usr/bin/env bash
set -euo pipefail

# labels-reconcile.sh — the automation LABELS.md promises: state labels are
# written by machinery, never by hand. Every run derives each open PR's
# state:* from GitHub's own facts (draft flag, requested reviewers, submitted
# reviews) and converges the labels to it, so a killed run or a hand-moved
# label heals on the next pass. Stale is judged from real activity — commits,
# comments, reviews — never from label churn, or the sweep would un-stale its
# own mark every tick.
#
# The verdict contract (CONTRIBUTING.md): reviews end in approve or
# request-changes. Reality check (#85 round 1): at least one live bot posts
# its agreement as a COMMENTED review and can never formally approve, which
# would park every fully-agreed PR in state:addressing forever. So COMMENTED
# reviews whose body carries a durable agreement signal count as approval —
# the workaround the state machine owes the fleet until every bot speaks the
# formal contract. Any verdict that counts toward needs-human must be bound
# to the CURRENT head SHA: GitHub keeps approvals alive across pushes, and a
# stale approval must never promote unreviewed code to the human.
#
# DRY_RUN=1 narrates every mutation instead of performing it (how this script
# is rehearsed against the live repo). A workflow_dispatch run also bootstraps
# the taxonomy (label create --force) — that heal is dispatch-only; the cron
# sweep tolerates a missing label rather than recreating it.
#
# The state machine below is pure (globals in, state out) and covered by
# fixture tests in test/labels-reconcile.sh.

HUMAN="${HUMAN_REVIEWER:-danmt}"
BOTS=(claude-bot-andresmgsl codex-bot-andresmgsl grok-bot-andresmgsl)
STATES=(state:building state:bots-reviewing state:addressing state:needs-human)
STALE_AFTER=$((48 * 3600))

log() { printf 'labels: %s\n' "$*"; }

run() { # every mutation goes through here — DRY_RUN=1 logs instead of doing
  if [ -n "${DRY_RUN:-}" ]; then log "DRY_RUN: $*"; else "$@"; fi
}

# ---------------------------------------------------------------------------
# The state machine. Pure functions over four globals, set per PR:
#   DRAFT        true|false
#   HEAD_SHA     the PR's current head commit
#   REQUESTED    newline-separated logins with a review currently requested
#   REVIEWS_JSON JSON array of submitted (non-PENDING) reviews
# ---------------------------------------------------------------------------

requested() { grep -qxF "$1" <<<"$REQUESTED"; }

agreement_signal() { # $1 = review body → 0 when it carries a durable agreement
  # the signals the live bots actually emit: grok "**Verdict: Approve**",
  # codex "Verdict: I agree with everything", claude "✅ … I agree with
  # everything". Conservative on purpose: "I agree with most" is NOT a match.
  grep -qiE 'verdict:? ?\**approve|i agree with everything|^✅' <<<"$1"
}

bot_verdict() { # $1 = login → MISSING | BLOCK | APPROVE | STALE | FEEDBACK
  local review state commit body
  review="$(jq -c --arg u "$1" \
    '[.[] | select(.user.login == $u)] | sort_by(.submitted_at) | last // empty' \
    <<<"$REVIEWS_JSON")"
  if [ -z "$review" ]; then echo MISSING; return; fi
  state="$(jq -r '.state' <<<"$review")"
  commit="$(jq -r '.commit_id' <<<"$review")"
  body="$(jq -r '.body // ""' <<<"$review")"
  case "$state" in
    CHANGES_REQUESTED)
      # blocks at ANY head — GitHub's own semantic: only a newer review
      # from the same reviewer clears it
      echo BLOCK ;;
    APPROVED)
      if [ "$commit" = "$HEAD_SHA" ]; then echo APPROVE; else echo STALE; fi ;;
    COMMENTED)
      if agreement_signal "$body"; then
        if [ "$commit" = "$HEAD_SHA" ]; then echo APPROVE; else echo STALE; fi
      else
        echo FEEDBACK
      fi ;;
    *) echo FEEDBACK ;;
  esac
}

decide_state() { # → the one state:* label this PR should carry
  if [ "$DRAFT" = true ]; then echo state:building; return; fi
  # an explicit human request outranks the bot rounds — it is the final
  # gate, and a maintainer pulling a PR to themselves early counts too
  if requested "$HUMAN"; then echo state:needs-human; return; fi
  local b v verdicts=""
  for b in "${BOTS[@]}"; do
    if requested "$b"; then echo state:bots-reviewing; return; fi
  done
  for b in "${BOTS[@]}"; do
    v="$(bot_verdict "$b")"
    if [ "$v" = MISSING ]; then echo state:bots-reviewing; return; fi
    verdicts="$verdicts $v"
  done
  case "$verdicts" in
    # FEEDBACK = a comment with no verdict → the agent owes the round-reply.
    # STALE = a verdict for an older head → the agent owes a re-request.
    *BLOCK* | *FEEDBACK* | *STALE*) echo state:addressing; return ;;
  esac
  # the bots all approve — but if the human's standing word is
  # changes-requested (and nobody re-requested them yet), the agent owes
  # fixes, not the human a nag
  if [ "$(bot_verdict "$HUMAN")" = BLOCK ]; then
    echo state:addressing
  else
    echo state:needs-human
  fi
}

# ---------------------------------------------------------------------------
# The sweep: fetch facts, decide, converge. One PR's failure never aborts the
# others — each PR reconciles in a subshell and a failure just logs.
# ---------------------------------------------------------------------------

bootstrap_labels() { # dispatch-only: ~20 upserts is too chatty for every cron tick
  while IFS='|' read -r name color desc; do
    [ -n "$name" ] || continue
    run gh label create "$name" -R "$REPO" --color "$color" --description "$desc" --force
  done <<'EOF'
state:building|FBCA04|PR is a draft — the coding agent is still building
state:bots-reviewing|1D76DB|Waiting on the bot reviewers to finish the round
state:addressing|D93F0B|All bots reviewed — coding agent owes the single reply + fixes
state:needs-human|8250DF|All bots approve — waiting on the human reviewer
stale|B60205|No activity for 48h — needs a poke (sweep-managed)
blocked|6A737D|Waiting on another PR or issue to land first
release|0E8A16|Release flow and version/packaging work
scope:bootstrap|C5DEF5|bootstrap — hardening a pristine server into a node
scope:users|C5DEF5|users-* — class model, apply/status, close-root
scope:runner|C5DEF5|runner-* — GitHub runner lifecycle
scope:coolify|C5DEF5|coolify-* — Coolify and backup install
scope:db|C5DEF5|db.sh — dump/restore
scope:installer|C5DEF5|install.sh — how rig lands on a machine
EOF
}

has_label() { grep -qxF "$1" <<<"$LABELS"; }

reconcile_pr() { # $1 = PR number; relies on the globals set from its fetch
  local n="$1" desired remove s args last_activity age

  desired="$(decide_state)"

  # encode the runbook's last step: the round passed → the human is asked,
  # once. The guard (never requested, never reviewed) makes it idempotent —
  # and the shared concurrency group in labels.yml makes it race-free.
  if [ "$desired" = state:needs-human ] && ! requested "$HUMAN" \
    && [ -z "$(jq -r --arg u "$HUMAN" '[.[] | select(.user.login == $u)] | last | .state // empty' <<<"$REVIEWS_JSON")" ]; then
    run gh api "repos/$REPO/pulls/$n/requested_reviewers" -f "reviewers[]=$HUMAN" --silent
    log "#$n: requested $HUMAN (round passed)"
  fi

  # ---- converge the state:* labels ----
  remove=""
  for s in "${STATES[@]}"; do
    if [ "$s" != "$desired" ] && has_label "$s"; then remove="$remove,$s"; fi
  done
  remove="${remove#,}"
  if ! has_label "$desired" || [ -n "$remove" ]; then
    args=(--add-label "$desired")
    [ -n "$remove" ] && args+=(--remove-label "$remove")
    if run gh issue edit "$n" -R "$REPO" "${args[@]}" >/dev/null; then
      log "#$n: state -> $desired${remove:+ (cleared $remove)}"
    else
      # a deleted label must not wedge the sweep — dispatch heals the taxonomy
      log "#$n: WARNING: label edit failed (missing label? run the workflow manually to bootstrap)"
    fi
  fi

  # ---- stale: real activity only, and blocked is legitimately quiet ----
  last_activity="$(
    {
      jq -r '.created_at' <<<"$PR_JSON"
      jq -r '.[].submitted_at' <<<"$REVIEWS_JSON"
      gh api --paginate "repos/$REPO/issues/$n/comments" --jq '.[].created_at'
      gh api --paginate "repos/$REPO/pulls/$n/comments" --jq '.[].created_at'
      gh api --paginate "repos/$REPO/pulls/$n/commits" --jq '.[].commit.committer.date'
    } | sort | tail -n1
  )"
  age=$((NOW - $(date -d "$last_activity" +%s)))
  if has_label blocked || [ "$age" -le "$STALE_AFTER" ]; then
    if has_label stale; then
      run gh issue edit "$n" -R "$REPO" --remove-label stale >/dev/null
      log "#$n: unstale"
    fi
  elif ! has_label stale; then
    run gh issue edit "$n" -R "$REPO" --add-label stale >/dev/null
    log "#$n: stale ($((age / 3600))h quiet)"
  fi
}

main() {
  REPO="${REPO:?set REPO to owner/name}"
  NOW="$(date +%s)"

  if [ "${GITHUB_EVENT_NAME:-}" = workflow_dispatch ]; then
    log "workflow_dispatch: bootstrapping the taxonomy"
    bootstrap_labels
  fi

  local n
  for n in $(gh pr list -R "$REPO" --state open --limit 100 --json number --jq '.[].number'); do
    (
      PR_JSON="$(gh api "repos/$REPO/pulls/$n")"
      DRAFT="$(jq -r '.draft' <<<"$PR_JSON")"
      HEAD_SHA="$(jq -r '.head.sha' <<<"$PR_JSON")"
      LABELS="$(jq -r '.labels[].name' <<<"$PR_JSON")"
      REQUESTED="$(jq -r '.requested_reviewers[].login' <<<"$PR_JSON")"
      # PENDING reviews are unsubmitted drafts in someone's browser — not a verdict
      REVIEWS_JSON="$(gh api --paginate "repos/$REPO/pulls/$n/reviews" --jq '.[]' \
        | jq -s '[.[] | select(.state != "PENDING")]')"
      reconcile_pr "$n"
    ) || log "#$n: reconcile failed — continuing with the remaining PRs"
  done
  log "reconciled."
}

# sourced by test/labels-reconcile.sh for the fixture tests; executed in CI
if [ "${BASH_SOURCE[0]}" = "$0" ]; then
  main "$@"
fi