#!/usr/bin/env bash
#
# Generic, host/repo/branch-aware deployment.
#
# One script for every project and every environment in the fleet. It is driven
# entirely by targets.json, so onboarding a new environment never means writing
# another copy of this logic inside a project repository.
#
# Invoked by the webhook daemon as:
#     cd-deploy --repo OWNER/NAME --ref refs/heads/BRANCH --sha FULLSHA [--event push]
#
# Deliberate properties, each one a lesson from the scripts this replaces:
#
#   * It never touches git. The compose stacks live in uas-ng and are refreshed
#     by that repo's own updater timer. A deploy script that runs `git reset
#     --hard` owns two jobs badly instead of one job well.
#   * It deploys the immutable <branch>-sha-<short> tag, then re-pins to the
#     resolved digest. Mutable tags like :latest and :test have already drifted
#     once in this fleet and served a broken build.
#   * It verifies the image's org.opencontainers.image.revision label equals the
#     commit that triggered the deploy, before changing anything.
#   * It never runs `docker compose down`, and most emphatically never
#     `down -v` -- `up -d` recreates exactly the services whose image changed.
#   * A target belonging to another host is a clean no-op, logged as such, and
#     never reported as a success.

set -Eeuo pipefail

SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
readonly SCRIPT_DIR
readonly CD_TARGET="${SCRIPT_DIR}/cd-target"

readonly STATE_DIR="${XDG_STATE_HOME:-${HOME}/.local/state}/cd-webhook"
readonly NO_MATCH=3

REPO=""
REF=""
SHA=""
EVENT="push"
DRY_RUN=0

# ---------------------------------------------------------------- logging ---

log()  { printf '%s  %s\n' "$(date -u '+%Y-%m-%dT%H:%M:%SZ')" "$*"; }
warn() { log "WARN  $*" >&2; }
die()  { log "ERROR $*" >&2; exit 1; }

usage() {
    sed -n '3,30p' "${BASH_SOURCE[0]}" | sed 's/^# \{0,1\}//'
    exit "${1:-0}"
}

# ------------------------------------------------------------ arg parsing ---

while [[ $# -gt 0 ]]; do
    case "$1" in
        --repo)     REPO="${2:?--repo needs a value}"; shift 2 ;;
        --ref)      REF="${2:?--ref needs a value}";   shift 2 ;;
        --sha)      SHA="${2:?--sha needs a value}";   shift 2 ;;
        --event)    EVENT="${2:?--event needs a value}"; shift 2 ;;
        --dry-run)  DRY_RUN=1; shift ;;
        -h|--help)  usage 0 ;;
        *)          die "unknown argument: $1 (try --help)" ;;
    esac
done

[[ -n "$REPO" ]] || die "--repo is required"
[[ -n "$REF"  ]] || die "--ref is required"
[[ -n "$SHA"  ]] || die "--sha is required"

if [[ "$EVENT" != "push" ]]; then
    log "ignoring event '${EVENT}' for ${REPO} (only 'push' deploys)"
    exit 0
fi

if [[ "$REF" != refs/heads/* ]]; then
    log "ignoring non-branch ref '${REF}' for ${REPO} (tags and deletes never deploy)"
    exit 0
fi
BRANCH="${REF#refs/heads/}"

if [[ ! "$SHA" =~ ^[0-9a-f]{40}$ ]]; then
    die "--sha must be a full 40-character hex commit, got: ${SHA}"
fi

# The all-zero SHA is how git spells "this ref was deleted".
if [[ "$SHA" == "0000000000000000000000000000000000000000" ]]; then
    log "ignoring branch deletion of ${REPO}@${BRANCH}"
    exit 0
fi

# ------------------------------------------------------ target resolution ---

set +e
resolved="$("$CD_TARGET" resolve --repo "$REPO" --branch "$BRANCH")"
resolve_rc=$?
set -e

if [[ $resolve_rc -eq $NO_MATCH ]]; then
    log "no target on $(hostname) for ${REPO}@${BRANCH} -- nothing to do here"
    exit 0
elif [[ $resolve_rc -ne 0 ]]; then
    die "target lookup failed for ${REPO}@${BRANCH} (exit ${resolve_rc})"
fi

eval "$resolved"

mkdir -p "$STATE_DIR"
readonly LOG_FILE="${STATE_DIR}/${CD_NAME}.log"
exec > >(stdbuf -oL tee -a "$LOG_FILE") 2>&1

log "=============================================================="
log "target      ${CD_NAME}  (${CD_ENV} on ${CD_RESOLVED_HOST})"
log "repo        ${REPO}@${BRANCH}"
log "commit      ${SHA}"
log "stack       ${CD_STACK_DIR}/${CD_COMPOSE_FILE}  [project ${CD_COMPOSE_PROJECT}]"
[[ $DRY_RUN -eq 1 ]] && log "mode        DRY RUN -- nothing will be changed"

[[ -d "$CD_STACK_DIR" ]] || die "stack directory missing: ${CD_STACK_DIR}"
[[ -f "${CD_STACK_DIR}/${CD_COMPOSE_FILE}" ]] \
    || die "compose file missing: ${CD_STACK_DIR}/${CD_COMPOSE_FILE}"

# ----------------------------------------------------------------- notify ---

notify() {
    local status="$1" message="$2" icon topic
    case "$status" in
        ok)   icon="✅" ;;
        fail) icon="❌" ;;
        *)    icon="ℹ️" ;;
    esac
    topic="${REPO//\//-}"
    curl -fsS --max-time 10 \
        -H "Title: ${CD_NAME} deploy" \
        -d "${icon} ${CD_NAME} (${CD_ENV}): ${message}" \
        "${CD_NTFY_BASE_URL}/${topic}" >/dev/null 2>&1 \
        || warn "ntfy notification failed (deploy outcome itself is unaffected)"
}

# ------------------------------------------------------------------- lock ---

# Serialise per target, not per host: a test deploy must not block a prod one.
readonly LOCK_FILE="${STATE_DIR}/${CD_NAME}.lock"
exec 9>"$LOCK_FILE"
log "waiting for deploy lock (${CD_LOCK_WAIT_SECONDS}s max)"
if ! flock -w "$CD_LOCK_WAIT_SECONDS" 9; then
    notify fail "timed out waiting for the deploy lock after ${CD_LOCK_WAIT_SECONDS}s"
    die "timed out waiting for deploy lock after ${CD_LOCK_WAIT_SECONDS}s"
fi
log "lock acquired"

# -------------------------------------------------------------- image tag ---

tag="$CD_IMAGE_TAG_TEMPLATE"
tag="${tag//\{branch\}/$BRANCH}"
tag="${tag//\{env\}/$CD_ENV}"
tag="${tag//\{sha\}/$SHA}"
tag="${tag//\{short7\}/${SHA:0:7}}"
tag="${tag//\{short12\}/${SHA:0:12}}"
readonly CANDIDATE="${CD_IMAGE_REPO}:${tag}"

log "candidate   ${CANDIDATE}"

# ------------------------------------------------------- wait for the image --

# The push webhook fires the moment the commit lands, which is well before CI
# has finished building. Poll rather than fail: the running container keeps
# serving throughout.
wait_for_image() {
    local elapsed=0
    while true; do
        if docker pull "$CANDIDATE" >/dev/null 2>&1; then
            log "image available after ${elapsed}s"
            return 0
        fi
        if (( elapsed >= CD_IMAGE_WAIT_SECONDS )); then
            return 1
        fi
        log "image not published yet, retrying in ${CD_IMAGE_POLL_INTERVAL}s (${elapsed}s elapsed)"
        sleep "$CD_IMAGE_POLL_INTERVAL"
        elapsed=$(( elapsed + CD_IMAGE_POLL_INTERVAL ))
    done
}

log "waiting for CI to publish the image (up to ${CD_IMAGE_WAIT_SECONDS}s)"
if [[ $DRY_RUN -eq 1 ]]; then
    log "dry run: skipping image wait"
elif ! wait_for_image; then
    notify fail "image ${CANDIDATE} never appeared (waited ${CD_IMAGE_WAIT_SECONDS}s) -- did CI fail?"
    die "image ${CANDIDATE} did not appear within ${CD_IMAGE_WAIT_SECONDS}s"
fi

# --------------------------------------------------- verify and pin digest ---

image_digest_ref() {
    docker image inspect --format '{{range .RepoDigests}}{{println .}}{{end}}' "$1" 2>/dev/null \
        | grep "^${CD_IMAGE_REPO}@" | head -n1
}

if [[ $DRY_RUN -eq 1 ]]; then
    DEPLOY_IMAGE="$CANDIDATE"
    log "dry run: would deploy ${DEPLOY_IMAGE}"
else
    revision="$(docker image inspect \
        --format '{{index .Config.Labels "org.opencontainers.image.revision"}}' \
        "$CANDIDATE" 2>/dev/null || true)"

    if [[ -z "$revision" || "$revision" == "<no value>" ]]; then
        warn "image carries no org.opencontainers.image.revision label; cannot prove provenance"
    elif [[ "$revision" != "$SHA" ]]; then
        notify fail "image ${CANDIDATE} is built from ${revision:0:12}, not ${SHA:0:12} -- refusing to deploy"
        die "provenance mismatch: ${CANDIDATE} declares revision ${revision}, expected ${SHA}"
    else
        log "provenance  revision label matches ${SHA:0:12}"
    fi

    DEPLOY_IMAGE="$(image_digest_ref "$CANDIDATE")"
    if [[ -z "$DEPLOY_IMAGE" ]]; then
        warn "could not resolve a digest for ${CANDIDATE}; deploying by tag instead"
        DEPLOY_IMAGE="$CANDIDATE"
    else
        log "pinned      ${DEPLOY_IMAGE}"
    fi
fi
readonly DEPLOY_IMAGE

# --------------------------------------------- remember what is running now ---

PREVIOUS_IMAGE="$(
    container_image="$(docker inspect --format '{{.Image}}' "$CD_CONTAINER" 2>/dev/null || true)"
    [[ -n "$container_image" ]] && image_digest_ref "$container_image" || true
)"
readonly PREVIOUS_IMAGE

if [[ -n "$PREVIOUS_IMAGE" ]]; then
    log "current     ${PREVIOUS_IMAGE}"
else
    log "current     (nothing running -- first deploy, or container absent)"
fi

# ----------------------------------------------------------------- deploy ---

compose_up() {
    local image="$1"
    # `up -d` recreates only what actually changed. `down` is deliberately not
    # used here: it causes avoidable downtime, and `down -v` would destroy the
    # data volumes these stacks depend on.
    ( cd "$CD_STACK_DIR" \
      && env "${CD_IMAGE_ENV_VAR}=${image}" \
             "${CD_PULL_POLICY_ENV_VAR}=missing" \
         timeout "$CD_COMPOSE_TIMEOUT_SECONDS" \
         docker compose -f "$CD_COMPOSE_FILE" -p "$CD_COMPOSE_PROJECT" up -d --no-build )
}

check_health() {
    local attempt=1 body
    while (( attempt <= CD_HEALTH_RETRIES )); do
        body="$(curl -fsS --max-time 5 "$CD_HEALTH_URL" 2>/dev/null || true)"
        if [[ -n "$body" ]]; then
            if python3 -c '
import json, sys
key, want = sys.argv[1], sys.argv[2]
try:
    data = json.loads(sys.stdin.read())
except Exception:
    sys.exit(1)
sys.exit(0 if str(data.get(key, "")).lower() == want.lower() else 1)
' "$CD_HEALTH_EXPECT_KEY" "$CD_HEALTH_EXPECT_VALUE" <<<"$body"; then
                log "health      ok after ${attempt} attempt(s): ${body}"
                return 0
            fi
        fi
        log "health      not ready (attempt ${attempt}/${CD_HEALTH_RETRIES}), retrying in ${CD_HEALTH_INTERVAL}s"
        sleep "$CD_HEALTH_INTERVAL"
        (( attempt++ ))
    done
    warn "health check never passed: last response was '${body:-<no response>}'"
    return 1
}

if [[ $DRY_RUN -eq 1 ]]; then
    log "dry run: would run docker compose up -d with ${CD_IMAGE_ENV_VAR}=${DEPLOY_IMAGE}"
    log "dry run: would health-check ${CD_HEALTH_URL}"
    log "dry run complete -- no changes made"
    exit 0
fi

log "deploying   ${DEPLOY_IMAGE}"
if ! compose_up "$DEPLOY_IMAGE"; then
    notify fail "docker compose up failed for ${SHA:0:12} -- stack left as-is"
    die "docker compose up failed"
fi

if check_health; then
    log "=== deploy succeeded: ${CD_NAME} now runs ${SHA:0:12} ==="
    notify ok "deployed ${SHA:0:12} (${DEPLOY_IMAGE##*@})"
    exit 0
fi

# ---------------------------------------------------------------- rollback ---

if [[ "$CD_ROLLBACK_ON_FAILURE" != "True" && "$CD_ROLLBACK_ON_FAILURE" != "true" ]]; then
    notify fail "health check failed for ${SHA:0:12}; rollback disabled, stack left on the new image"
    die "health check failed and rollback is disabled for this target"
fi

if [[ -z "$PREVIOUS_IMAGE" ]]; then
    notify fail "health check failed for ${SHA:0:12} and there is no previous image to roll back to"
    die "health check failed; no previous image recorded, leaving the stack as it is"
fi

warn "health check failed -- rolling back to ${PREVIOUS_IMAGE}"
if compose_up "$PREVIOUS_IMAGE" && check_health; then
    notify fail "deploy of ${SHA:0:12} failed health check; rolled back to the previous image successfully"
    die "deploy failed health check; rolled back to ${PREVIOUS_IMAGE}"
fi

notify fail "deploy of ${SHA:0:12} failed AND rollback failed -- ${CD_NAME} needs manual attention now"
die "deploy failed and rollback also failed; manual intervention required"