# ==============================================================================
# Findmvt.cmake
# ==============================================================================
# This module provides the Mapbox Vector Tile Specification (v2.1) for use
# with protozero. The .proto file is downloaded as a reference; actual decoding
# is done manually via protozero (no code generation step required).
#
# Targets provided:
#   mvt::mvt - Interface target (pulls in protozero)
#
# Variables set:
#   mvt_FOUND       - TRUE if mvt is available
#   mvt_LIBRARIES   - The library target (mvt::mvt)
#   mvt_PROTO_FILE  - Path to the downloaded vector_tile.proto
# ==============================================================================

if (DEFINED _FINDMVT_INCLUDED)
    return()
endif()
set(_FINDMVT_INCLUDED TRUE)

# ------------------------------------------------------------------------------
# Protozero (the actual parsing library)
# ------------------------------------------------------------------------------
find_package(protozero REQUIRED)

# ------------------------------------------------------------------------------
# Download .proto file (reference only — no code generation)
# ------------------------------------------------------------------------------
set(_MVT_PROTO_DIR  "${CMAKE_CURRENT_BINARY_DIR}/mvt_proto")
set(_MVT_PROTO_FILE "${_MVT_PROTO_DIR}/vector_tile.proto")

file(MAKE_DIRECTORY "${_MVT_PROTO_DIR}")

if (NOT EXISTS "${_MVT_PROTO_FILE}")
    message(STATUS "Downloading vector_tile.proto")
    file(DOWNLOAD
        "https://raw.githubusercontent.com/mapbox/vector-tile-spec/refs/heads/master/2.1/vector_tile.proto"
        "${_MVT_PROTO_FILE}"
        STATUS _download_status
    )
    list(GET _download_status 0 _download_code)
    if (NOT _download_code EQUAL 0)
        list(GET _download_status 1 _download_error)
        message(FATAL_ERROR "Failed to download vector_tile.proto: ${_download_error}")
    endif()
endif()

message(STATUS "MVT proto: ${_MVT_PROTO_FILE}")

# ------------------------------------------------------------------------------
# Interface target
# ------------------------------------------------------------------------------
if (NOT TARGET mvt::mvt)
    add_library(mvt INTERFACE)
    target_link_libraries(mvt INTERFACE protozero::protozero)
    add_library(mvt::mvt ALIAS mvt)
endif()

set(mvt_FOUND      TRUE)
set(mvt_LIBRARIES  mvt::mvt)
set(mvt_PROTO_FILE "${_MVT_PROTO_FILE}" CACHE FILEPATH "Path to vector_tile.proto")