CustomExportFilter.lua

--[[============================================================================
    CustomExportFilter.lua

    Export filter — injects custom XMP metadata
    into exported files (JPG/TIFF) using ExifTool.

    Filter API:
    - for rendition in filterContext:renditions{ stopIfCanceled = true }
    - rendition:waitForRender() → success, path
    - rendition.photo → LrPhoto

============================================================================--]]

local LrDialogs     = import "LrDialogs"
local LrFileUtils   = import "LrFileUtils"
local LrPathUtils   = import "LrPathUtils"
local LrTasks       = import "LrTasks"
local LrView        = import "LrView"
local LrStringUtils = import "LrStringUtils"

local SC  = require "SharedConfig"
local Log = require "PluginLogger"

local logger = Log.getLogger("ExportFilter")

--------------------------------------------------------------------------
-- Helpers
--------------------------------------------------------------------------

local function isExifToolAvailable()
    local cmd = WIN_ENV and "where exiftool >NUL 2>&1"
                         or "which exiftool >/dev/null 2>&1"
    return LrTasks.execute(cmd) == 0
end

--------------------------------------------------------------------------
-- Argfile and ExifTool
--------------------------------------------------------------------------

local function writeArgFile(tmpDir, idx, photo, filePath)
    local argPath = LrPathUtils.child(
        tmpDir, "custmeta_e_" .. tostring(idx) .. ".txt")

    local lines = {}

    if WIN_ENV then
        table.insert(lines, "-charset")
        table.insert(lines, "filename=utf8")
    end

    local hasData = false

    for _, field in ipairs(SC.FIELD_MAP) do
        local value = photo:getPropertyForPlugin(SC.PLUGIN_ID, field.id)
        if value then
            local trimmed = LrStringUtils.trimWhitespace(tostring(value))
            if trimmed ~= "" then
                hasData = true
                table.insert(lines, string.format(
                    "-XMP-%s:%s=%s", SC.XMP_PREFIX, field.xmpTag, trimmed))
            end
        end
    end

    if not hasData then return nil end

    table.insert(lines, "-overwrite_original")
    table.insert(lines, filePath)

    local f = io.open(argPath, "wb")
    if not f then return nil end
    f:write(table.concat(lines, "\n") .. "\n")
    f:close()

    return argPath
end

local function runExifTool(configPath, argPath, tmpDir, idx)
    local outPath = LrPathUtils.child(tmpDir, "custmeta_e_out_" .. tostring(idx) .. ".txt")

    local cmd = string.format('exiftool -config "%s" -@ "%s" > "%s" 2>&1',
        configPath, argPath, outPath)

    if Log.isEnabled("trace") then logger:trace("CMD: " .. cmd) end

    local exitCode = LrTasks.execute(cmd)

    if Log.isEnabled("trace") then
        logger:trace("Exit: " .. tostring(exitCode))
        if exitCode ~= 0 then
            logger:trace("Output: " .. SC.readFileContents(outPath))
        end
    end

    SC.safeDelete(outPath)
    return exitCode == 0
end

--------------------------------------------------------------------------
-- UI Section
--------------------------------------------------------------------------

local function sectionForFilterInDialog(viewFactory, propertyTable)
    return {
        title = "Custom XMP Metadata",
        viewFactory:row {
            viewFactory:static_text {
                title = "Injects custom metadata from the catalog\n"
                     .. "into XMP embedded in the exported file.\n\n"
                     .. "Requires ExifTool (exiftool.org).",
                fill_horizontal = 1,
            },
        },
        viewFactory:row {
            viewFactory:checkbox {
                title = "Inject custom XMP metadata",
                value = LrView.bind("embedCustomXMP"),
            },
        },
    }
end

--------------------------------------------------------------------------
-- Post-process
--------------------------------------------------------------------------

local function postProcessRenderedPhotos(functionContext, filterContext)

    if not filterContext then return end

    local propertyTable = filterContext.propertyTable

    if not (propertyTable and propertyTable.embedCustomXMP) then
        for rendition in filterContext:renditions{ stopIfCanceled = true } do
            rendition:waitForRender()
        end
        return
    end

    if not isExifToolAvailable() then
        LrDialogs.showError("ExifTool not found in PATH.\n"
                         .. "Install from https://exiftool.org")
        for rendition in filterContext:renditions{ stopIfCanceled = true } do
            rendition:waitForRender()
        end
        return
    end

    local tmpDir     = LrPathUtils.getStandardFilePath("temp")
    local configPath = SC.writeExifToolConfig(tmpDir, "custmeta_e.config")

    if not configPath then
        for rendition in filterContext:renditions{ stopIfCanceled = true } do
            rendition:waitForRender()
        end
        return
    end

    local cleanUp    = {}
    local embedCount = 0
    local totalCount = 0

    for rendition in filterContext:renditions{ stopIfCanceled = true } do
        totalCount = totalCount + 1
        local success, pathOrMsg = rendition:waitForRender()

        if success then
            local argPath = writeArgFile(tmpDir, totalCount, rendition.photo, pathOrMsg)
            if argPath then
                table.insert(cleanUp, argPath)
                if runExifTool(configPath, argPath, tmpDir, totalCount) then
                    embedCount = embedCount + 1
                else
                    logger:warn("ExifTool failed: " .. pathOrMsg)
                end
            end
        else
            logger:warn("Render failed: " .. tostring(pathOrMsg))
        end
    end

    if Log.isEnabled("trace") then
        logger:trace("Embedded: " .. embedCount .. "/" .. totalCount)
    end

    for _, p in ipairs(cleanUp) do SC.safeDelete(p) end
    SC.safeDelete(configPath)
end

--------------------------------------------------------------------------
-- Export Filter Provider
--------------------------------------------------------------------------

return {
    exportPresetFields = {
        { key = "embedCustomXMP", default = true },
    },
    sectionForFilterInDialog     = sectionForFilterInDialog,
    postProcessRenderedPhotos    = postProcessRenderedPhotos,
}