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

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
INVENTORY_FILE="${REPO_ROOT}/homelab.yml"
README_TEMPLATE="${REPO_ROOT}/README.md.tmpl"
README_OUTPUT="${REPO_ROOT}/README.md"
TEMPLATES_DIR="${REPO_ROOT}/docs/templates"
DOCS_DIR="${REPO_ROOT}/docs"

usage() {
    cat <<'USAGE'
Usage: scripts/render-docs [--check]

Render generated Markdown docs from repo-local templates.

Options:
  --check   fail if generated docs differ from committed output
USAGE
}

read_inventory_value() {
    local path="$1"

    python3 - "${INVENTORY_FILE}" "${path}" <<'PY'
import re
import sys

inventory_file, requested_path = sys.argv[1:3]
stack = []
values = {}
pattern = re.compile(r"^(\s*)([A-Za-z_][A-Za-z0-9_]*):(?:\s*(.*?))?\s*$")

with open(inventory_file, encoding="utf-8") as handle:
    for raw_line in handle:
        if not raw_line.strip() or raw_line.lstrip().startswith("#") or raw_line.lstrip().startswith("- "):
            continue
        match = pattern.match(raw_line.rstrip("\n"))
        if not match:
            continue
        indent = len(match.group(1))
        key = match.group(2)
        value = (match.group(3) or "").strip()
        while stack and stack[-1][0] >= indent:
            stack.pop()
        current_path = ".".join([item[1] for item in stack] + [key])
        if value == "":
            stack.append((indent, key))
            continue
        if " #" in value:
            value = value.split(" #", 1)[0].strip()
        values[current_path] = value.strip("\"'")

value = values.get(requested_path)
if not value:
    raise SystemExit(1)
print(value)
PY
}

render_template() {
    local template_path="$1"
    local output_path="$2"
    local main_script="$3"

    if [[ ! -f "$template_path" ]]; then
        return 1
    fi

    sed "s/{{[[:space:]]*main_script[[:space:]]*}}/${main_script}/g" "$template_path" > "$output_path"
}

main() {
    local mode="render"
    local main_script
    local rendered_tmp

    case "${1:-}" in
        "")
            ;;
        --check)
            mode="check"
            ;;
        -h | --help)
            usage
            return 0
            ;;
        *)
            usage >&2
            return 2
            ;;
    esac

    if [[ ! -s "${INVENTORY_FILE}" ]]; then
        printf 'Missing homelab inventory: %s\n' "${INVENTORY_FILE}" >&2
        return 1
    fi

    main_script="$(read_inventory_value metadata.main_script)"
    if [[ -z "${main_script}" ]]; then
        printf 'homelab.yml metadata.main_script must not be empty\n' >&2
        return 1
    fi

    # 1. Render README
    rendered_tmp=$(mktemp)
    render_template "${README_TEMPLATE}" "$rendered_tmp" "${main_script}"

    if [[ "${mode}" == "check" ]]; then
        if ! cmp -s "$rendered_tmp" "${README_OUTPUT}"; then
            printf 'Generated README.md is stale.\n' >&2
            diff -u "${README_OUTPUT}" "$rendered_tmp" || true
            rm -f "$rendered_tmp"
            return 1
        fi
    else
        mv "$rendered_tmp" "${README_OUTPUT}"
    fi
    rm -f "$rendered_tmp"

    # 2. Render Modular Docs
    for tmpl in "${TEMPLATES_DIR}"/*.tmpl; do
        [[ -e "$tmpl" ]] || continue
        local filename
        local output_file

        filename=$(basename "$tmpl" .md.tmpl)
        output_file="${DOCS_DIR}/${filename}.md"
        
        if [[ "${mode}" == "check" ]]; then
            rendered_tmp=$(mktemp)
            render_template "$tmpl" "$rendered_tmp" "${main_script}"
            if ! cmp -s "$rendered_tmp" "$output_file"; then
                printf 'Generated %s is stale.\n' "$output_file" >&2
                diff -u "$output_file" "$rendered_tmp" || true
                rm -f "$rendered_tmp"
                return 1
            fi
            rm -f "$rendered_tmp"
        else
            render_template "$tmpl" "$output_file" "${main_script}"
        fi
    done

    # 3. Render Service Catalog
    if [[ "${mode}" == "check" ]]; then
        "${REPO_ROOT}/scripts/render-service-catalog" --check
    else
        "${REPO_ROOT}/scripts/render-service-catalog"
    fi

    if [[ "${mode}" == "render" ]]; then
        printf 'Successfully rendered all documentation from templates.\n'
    else
        printf 'All docs are current.\n'
    fi
}

main "$@"