WriteMetadataToXMP.lua

--[[============================================================================
    WriteMetadataToXMP.lua

    Library → Plugin Extras → "Write Custom Metadata to XMP"

    For RAW → sidecar .xmp    |    For JPG/TIFF → embedded in the file

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

local LrApplication     = import "LrApplication"
local LrDialogs         = import "LrDialogs"
local LrFunctionContext = import "LrFunctionContext"
local LrPathUtils       = import "LrPathUtils"
local LrProgressScope   = import "LrProgressScope"
local LrStringUtils     = import "LrStringUtils"
local LrTasks           = import "LrTasks"
local LrFileUtils       = import "LrFileUtils"

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

local logger = Log.getLogger("WriteXMP")

--------------------------------------------------------------------------
-- Argfile
--------------------------------------------------------------------------

local function writeArgFile(tmpDir, suffix, photo, targetPath)
    local argPath = LrPathUtils.child(tmpDir, "custmeta_w_" .. suffix .. ".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, targetPath)

    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

--------------------------------------------------------------------------
-- ExifTool
--------------------------------------------------------------------------

local function runExifTool(configPath, argPath, tmpDir, suffix)
    local outPath = LrPathUtils.child(tmpDir, "custmeta_out_" .. suffix .. ".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

--------------------------------------------------------------------------
-- Main logic
--------------------------------------------------------------------------

LrTasks.startAsyncTask(function()
    LrFunctionContext.callWithContext("WriteCustomXMP", function(context)

        context:addFailureHandler(function(_, msg)
            logger:error("FAILURE: " .. tostring(msg))
            LrDialogs.showError("Plugin error:\n\n" .. tostring(msg))
        end)

        local catalog = LrApplication.activeCatalog()
        local photos  = catalog:getTargetPhotos()

        if #photos == 0 then
            LrDialogs.message("No photos selected",
                "Select photos to which you want to write XMP metadata.", "info")
            return
        end

        local result = LrDialogs.confirm(
            "Write custom metadata to XMP?",
            string.format(
                "This operation applies to %d photos.\n\n"
             .. "RAW → sidecar .xmp\nJPG/TIFF → embedded in the file\n\n"
             .. "Requires: ExifTool (exiftool.org)", #photos),
            "Write", "Cancel"
        )
        if result ~= "ok" then return end

        -- Check ExifTool
        local checkCmd = WIN_ENV and "where exiftool >NUL 2>&1"
                                  or "which exiftool >/dev/null 2>&1"
        if LrTasks.execute(checkCmd) ~= 0 then
            LrDialogs.showError("ExifTool not found in PATH.\n"
                             .. "Install from https://exiftool.org")
            return
        end

        local tmpDir     = LrPathUtils.getStandardFilePath("temp")
        local configPath = SC.writeExifToolConfig(tmpDir, "custmeta_w.config")
        if not configPath then
            LrDialogs.showError("Cannot create configuration file.")
            return
        end

        local progress = LrProgressScope {
            title = "Writing XMP metadata...", functionContext = context,
        }

        local ok, skip, fail = 0, 0, 0
        local sidecarN = 0
        local failNames, cleanUp = {}, {}

        for i, photo in ipairs(photos) do
            if progress:isCanceled() then break end
            progress:setPortionComplete(i - 1, #photos)
            progress:setCaption(string.format("File %d / %d", i, #photos))

            local filePath = photo:getRawMetadata("path")

            if not filePath or not LrFileUtils.exists(filePath) then
                skip = skip + 1
            else
                local targetPath, isSidecar = SC.getTargetPath(filePath)
                if isSidecar then sidecarN = sidecarN + 1 end

                local argPath = writeArgFile(tmpDir, tostring(i), photo, targetPath)
                if argPath then
                    table.insert(cleanUp, argPath)
                    if runExifTool(configPath, argPath, tmpDir, tostring(i)) then
                        ok = ok + 1
                    else
                        fail = fail + 1
                        table.insert(failNames, LrPathUtils.leafName(filePath))
                    end
                else
                    skip = skip + 1
                end
            end
        end

        progress:done()

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

        -- Summary
        local msg = string.format(
            "Written: %d (sidecar .xmp: %d)\nSkipped: %d\nErrors: %d",
            ok, sidecarN, skip, fail)
        if #failNames > 0 then
            msg = msg .. "\n\nFiles with errors:\n"
            for idx = 1, math.min(#failNames, 10) do
                msg = msg .. "  - " .. failNames[idx] .. "\n"
            end
        end
        LrDialogs.message("XMP write complete", msg,
            fail > 0 and "warning" or "info")

    end)
end)