#!/bin/bash
set -euo pipefail

# ── Colors ───────────────────────────────────────────────────────────
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
NC='\033[0m'

# ── Logging ──────────────────────────────────────────────────────────
log_info()  { printf "${CYAN}[INFO]${NC}  %s\n" "$*"; }
log_warn()  { printf "${YELLOW}[WARN]${NC}  %s\n" "$*"; }
log_ok()    { printf "${GREEN}[ OK ]${NC}  %s\n" "$*"; }
log_error() { printf "${RED}[ERR]${NC}   %s\n" "$*" >&2; }

# ── Usage ────────────────────────────────────────────────────────────
usage() {
    cat <<EOF
Usage: $(basename "$0") [OPTIONS]

Clone every project from every group (and subgroups, recursively) on a
GitLab instance, preserving the path_with_namespace directory structure.

Options:
    -h, --help               Show this help
    -t, --token-file=FILE    File containing the GitLab personal access token
    -g, --gitlab-url=URL     GitLab instance URL (default: https://git.mws-team.ru)

Examples:
    $(basename "$0") -t ~/.gitlab_token
    $(basename "$0") --token-file=token.txt --gitlab-url=https://gitlab.com
EOF
    exit 1
}

# ── Dependency check ─────────────────────────────────────────────────
for cmd in curl jq git; do
    if ! command -v "$cmd" &>/dev/null; then
        log_error "Required command not found: ${cmd}"
        exit 1
    fi
done

# ── Parse arguments ──────────────────────────────────────────────────
GITLAB_URL="https://git.mws-team.ru"
TOKEN_FILE=""

translated=()
while (( $# )); do
    case "$1" in
        --help)          translated+=("-h"); shift ;;
        --token-file=*)  translated+=("-t" "${1#*=}"); shift ;;
        --gitlab-url=*)  translated+=("-g" "${1#*=}"); shift ;;
        --)              translated+=("--"); shift; translated+=("$@"); break ;;
        *)               translated+=("$1"); shift ;;
    esac
done
set -- "${translated[@]}"

while getopts ":ht:g:" opt; do
    case "$opt" in
        h)  usage ;;
        t)  TOKEN_FILE="$OPTARG" ;;
        g)  GITLAB_URL="$OPTARG" ;;
        :)  log_error "Missing argument for -${OPTARG}"; usage ;;
        \?) log_error "Invalid option: -${OPTARG}"; usage ;;
    esac
done
shift $((OPTIND - 1))

# ── Validate inputs ─────────────────────────────────────────────────
[[ -z "$TOKEN_FILE" ]]   && { log_error "Missing --token-file"; usage; }
[[ -z "$GITLAB_URL" ]]   && { log_error "Missing --gitlab-url"; usage; }
[[ ! -f "$TOKEN_FILE" ]] && { log_error "Token file not found: ${TOKEN_FILE}"; exit 1; }

GITLAB_URL="${GITLAB_URL%/}"

TOKEN="$(<"$TOKEN_FILE")"
readonly TOKEN GITLAB_URL

# ── GitLab API helpers ───────────────────────────────────────────────

# Authenticated GET request; returns JSON body.
gitlab_get() {
    curl --silent --fail --header "Authorization: Bearer ${TOKEN}" "$1"
}

# Return total page count for a paginated endpoint.
gitlab_total_pages() {
    local headers
    headers="$(curl -X HEAD --silent -w '%{header_json}' \
        --header "Authorization: Bearer ${TOKEN}" \
        -o /dev/null "$1" 2>/dev/null)" || true

    local pages
    pages="$(echo "$headers" | jq -r '."x-total-pages"[0] // "1"')"
    [[ -z "$pages" || "$pages" == "null" ]] && pages=1
    echo "$pages"
}

# Iterate all pages of an endpoint, call a callback with each extracted value.
# Usage: gitlab_paginate "URL?per_page=100" '.[].id' callback_fn
gitlab_paginate() {
    local base_url="$1"
    local jq_filter="$2"
    local callback="$3"

    local total_pages
    total_pages="$(gitlab_total_pages "$base_url")"

    local page
    for (( page = 1; page <= total_pages; page++ )); do
        local response
        response="$(gitlab_get "${base_url}&page=${page}")" || {
            log_warn "API request failed: ${base_url}&page=${page}"
            continue
        }

        local item
        while IFS= read -r item; do
            [[ -z "$item" ]] && continue
            "$callback" "$item"
        done < <(echo "$response" | jq -r "$jq_filter")
    done
}

# ── Clone a single project ──────────────────────────────────────────
CLONE_COUNT=0
SKIP_COUNT=0

clone_project() {
    local project_id="$1"

    local project_json
    project_json="$(gitlab_get "${GITLAB_URL}/api/v4/projects/${project_id}")" || {
        log_warn "Failed to fetch project ${project_id}"
        return
    }

    local path_ns ssh_url
    path_ns="$(echo "$project_json"  | jq -r '.path_with_namespace')"
    ssh_url="$(echo "$project_json"  | jq -r '.ssh_url_to_repo')"

    if [[ -z "$path_ns" || "$path_ns" == "null" ]]; then
        log_warn "Could not determine path for project ${project_id} — skipping"
        return
    fi

    if [[ -d "$path_ns" ]]; then
        log_info "Already cloned: ${path_ns}"
        (( SKIP_COUNT++ )) || true
        return
    fi

    log_info "Cloning: ${path_ns}"
    mkdir -p "$(dirname "$path_ns")"
    if git clone --quiet "$ssh_url" "$path_ns"; then
        log_ok "Cloned: ${path_ns}"
        (( CLONE_COUNT++ )) || true
    else
        log_warn "git clone failed for ${path_ns}"
    fi
}

# ── Clone all projects in a group ────────────────────────────────────
clone_group_projects() {
    local group_id="$1"
    gitlab_paginate \
        "${GITLAB_URL}/api/v4/groups/${group_id}/projects?per_page=100&archived=no" \
        '.[].id' clone_project
}

# ── Process a group and all its subgroups recursively ────────────────
process_group() {
    local group_id="$1"

    clone_group_projects "$group_id"

    # Collect subgroup IDs, then recurse
    local subgroup_ids=()
    while IFS= read -r sid; do
        [[ -z "$sid" ]] && continue
        subgroup_ids+=("$sid")
    done < <(
        local total
        total="$(gitlab_total_pages "${GITLAB_URL}/api/v4/groups/${group_id}/subgroups?per_page=100")"
        for (( p = 1; p <= total; p++ )); do
            gitlab_get "${GITLAB_URL}/api/v4/groups/${group_id}/subgroups?per_page=100&page=${p}" \
                | jq -r '.[].id'
        done
    )

    local sid
    for sid in "${subgroup_ids[@]}"; do
        log_info "Entering subgroup ${sid}"
        process_group "$sid"
    done
}

# ── Main ─────────────────────────────────────────────────────────────
main() {
    log_info "GitLab URL:  ${GITLAB_URL}"
    log_info "Token file:  ${TOKEN_FILE}"
    echo

    # Iterate over every top-level group visible to the token
    gitlab_paginate \
        "${GITLAB_URL}/api/v4/groups?per_page=100&top_level_only=true" \
        '.[].id' process_group

    echo
    log_ok "Done — cloned ${CLONE_COUNT} repo(s), skipped ${SKIP_COUNT} already present"
}

main