*! version 1.2.3 20261030 github.com/mdroste/stata-ctools

program define cexport, rclass
    version 14.1

    * Check observation limit (Stata plugin API limitation)
    if _N > 2147483647 {
        di as error "ctools does not support datasets exceeding 2^31 (2.147 billion) observations"
        di as error "This is a limitation of Stata's plugin API"
        exit 920
    }

    * Parse the subcommand
    gettoken subcmd 0 : 0, parse(" ,")
    if inlist("`subcmd'", "delim", "delimi", "delimit", "delimite") local subcmd "delimited"
    if "`subcmd'" == "dbas" local subcmd "dbase"
    if inlist("`subcmd'", "exc", "exce") local subcmd "excel"

    if "`subcmd'" == "sasxport" & _caller()<16 local subcmd "sasxport5"
    if "`subcmd'" == "shp" {
        _cio_shp_export `0'
        return add
        exit
    }

    if inlist("`subcmd'", "sas", "spss", "sasxport5", "sasxport8", "dbase") {
        _cio_export `subcmd' `0'
        return add
        exit
    }

    if "`subcmd'" == "excel" {
        * Dispatch to Excel export handler
        cexport_excel `0'
        return add
        exit
    }
    else if "`subcmd'" != "delimited" {
        di as error "cexport: unknown subcommand `subcmd'"
        di as error "Supported file formats: delimited, excel, spss, sasxport5, sasxport8, dbase, shp, sas"
        exit 198
    }

    * Check that data is loaded (match export delimited rc=102)
    if c(k) == 0 {
        di as error "no variables defined"
        exit 102
    }

    * Parse the rest with export delimited-style syntax
    * Support both "using filename" and just "filename" (like export delimited does)
    syntax [anything] [using/] [if] [in], [Delimiter(string) NOVARNames QUOTE ///
        NOQUOTEif REPLACE DATAfmt DATEString(string) NOLabel Verbose ///
        MMAP NOFSYNC DIRECT PREFAULT CRLF NOPARALLEL THReads(integer 0)]

    * Handle filename - can come from using/ or as last positional argument
    if `"`using'"' == "" & `"`anything'"' != "" {
        gettoken using extra : anything
        if trim(`"`extra'"') != "" {
            di as error "specify using before the filename when selecting variables"
            exit 198
        }
        local anything ""
    }
    if `"`using'"' == "" {
        di as error "cexport delimited: filename required"
        di as error "Syntax: cexport delimited [varlist] [using] filename [, options]"
        exit 198
    }
    mata: st_local("__basename", pathbasename(st_local("using")))
    if !strpos(`"`__basename'"', ".") local using `"`using'.csv"'
    * Resolve varlist from anything.
    * Must happen BEFORE marksample, which creates a touse tempvar
    * that ds would include in the variable list.
    if strtrim(`"`anything'"') != "" {
        unab varlist : `anything'
    }
    else {
        qui ds
        local varlist `r(varlist)'
    }

    * Mark sample
    marksample touse, novarlist

    * Validate file
    if "`replace'" == "" {
        capture confirm file `"`using'"'
        if !_rc {
            di as error "file `using' already exists"
            di as error "use the replace option to overwrite"
            exit 602
        }
    }

    * Set default delimiter
    if `"`delimiter'"' == "" {
        local delimiter ","
    }

    * Handle tab delimiter - pass "tab" keyword to plugin (not actual char)
    local plugin_delim `"`delimiter'"'
    if `"`delimiter'"' == "tab" | `"`delimiter'"' == "\t" {
        local plugin_delim "tab"
        local delim_display "tab"
    }
    else {
        local delim_display `"`delimiter'"'
        * Validate delimiter (tab is handled specially)
        if length(`"`delimiter'"') != 1 {
            di as error "cexport: delimiter must be a single character"
            exit 198
        }
    }

    * Handle value labels: decode labeled variables unless nolabel specified
    local export_varlist ""
    local decoded_vars ""
    local original_names ""
    * Preformatted string columns, which the writer never quotes
    local formatted_vars ""
    if "`nolabel'" == "" {
        * Default: export value labels
        foreach var of local varlist {
            * Check if variable has a value label attached
            local vallbl : value label `var'
            if "`vallbl'" != "" {
                * Has value label - decode to temporary string variable
                tempvar decoded_`var'
                qui decode `var', gen(`decoded_`var'')
                qui recast str2045 `decoded_`var''
                local labfmt : format `var'
                if !(substr("`labfmt'",1,2) == "%t" | substr("`labfmt'",1,3) == "%-t") local labfmt "%18.0g"
                * Under quote, native export quotes only the label text; a value
                * without a label is still written as an unquoted number (and
                * system missing as an empty unquoted field). Quote the label
                * cells here and mark the column preformatted so the writer
                * leaves the numeric fallbacks bare.
                if "`quote'" != "" {
                    qui replace `decoded_`var'' = char(34) + subinstr(`decoded_`var'', char(34), char(34)+char(34), .) + char(34) if `decoded_`var''!=""
                    local formatted_vars `formatted_vars' `decoded_`var''
                }
                qui replace `decoded_`var'' = strtrim(string(`var',"`labfmt'")) if `decoded_`var''=="" & `var' != .
                local export_varlist `export_varlist' `decoded_`var''
                local decoded_vars `decoded_vars' `decoded_`var''
                local original_names `original_names' `var'
            }
            else {
                local export_varlist `export_varlist' `var'
            }
        }
    }
    else {
        * nolabel specified: export raw numeric values
        local export_varlist `varlist'
    }

    * Prepare display-format fields; the C writer still owns CSV encoding and I/O.
    * Native export writes date/time variables (%t and %-t) with their display
    * format by default; datafmt extends that to every numeric variable.
    local new_export_varlist ""
    local export_idx = 0
    foreach var of local export_varlist {
        local ++export_idx
        local origvar : word `export_idx' of `varlist'
        local fmt : format `origvar'
        local is_time = substr("`fmt'",1,2) == "%t" | substr("`fmt'",1,3) == "%-t"
        capture confirm numeric variable `var'
        if !_rc & ("`datafmt'" != "" | `is_time') {
            if `"`datestring'"' != "" & `is_time' local fmt `"`datestring'"'
            tempvar formatted
            quietly gen `formatted' = cond(`var' == ., "", strtrim(string(`var', `"`fmt'"')))
            local new_export_varlist `new_export_varlist' `formatted'
            local formatted_vars `formatted_vars' `formatted'
        }
        else local new_export_varlist `new_export_varlist' `var'
    }
    local export_varlist `new_export_varlist'

    * Count variables and observations
    local nvars : word count `varlist'
    qui count `if' `in'
    local nobs = r(N)

    if `nvars' == 0 {
        di as error "cexport: no variables to export"
        exit 198
    }

    * Load the platform-appropriate ctools plugin if not already loaded
    _ctools_load
    * Stata scopes plugin registrations to the calling ado program.
    capture program ctools_plugin, plugin using("`__ctools_plugin'")
    if _rc != 0 & _rc != 110 exit 601
    capture confirm number 0

    * Build plugin arguments
    local opt_noheader = cond("`novarnames'" != "", "noheader", "")
    local opt_quote = cond("`quote'" != "", "quote", "")
    local opt_noquoteif = cond("`noquoteif'" != "", "noquoteif", "")
    local opt_verbose = cond("`verbose'" != "", "verbose", "")

    * Performance options
    local opt_mmap = cond("`mmap'" != "", "mmap", "")
    local opt_nofsync = cond("`nofsync'" != "", "nofsync", "")
    local opt_direct = cond("`direct'" != "", "direct", "")
    local opt_prefault = cond("`prefault'" != "", "prefault", "")
    local opt_crlf = cond("`crlf'" != "", "crlf", "")
    local opt_noparallel = cond("`noparallel'" != "", "noparallel", "")

    * Build threads option string
    local threads_code ""
    if `threads' > 0 {
        local threads_code "threads(`threads')"
    }



    * Pass variable storage types to the plugin
    * Types: 1=byte, 2=int, 3=long, 4=float, 5=double, 0=string
    local vartypes ""
    foreach var of local export_varlist {
        local vtype : type `var'
        if `: list var in formatted_vars' {
            local vartypes `vartypes' 6
        }
        else if "`vtype'" == "byte" {
            local vartypes `vartypes' 1
        }
        else if "`vtype'" == "int" {
            local vartypes `vartypes' 2
        }
        else if "`vtype'" == "long" {
            local vartypes `vartypes' 3
        }
        else if "`vtype'" == "float" {
            local vartypes `vartypes' 4
        }
        else if "`vtype'" == "double" {
            local vartypes `vartypes' 5
        }
        else {
            * String type (str#, strL)
            local vartypes `vartypes' 0
        }
    }


    * Each metadata field has an independent local; no aggregate buffer limit.
    local metadata_count : word count `varlist'
    forvalues metadata_i=1/`metadata_count' {
        local __cexport_name_`metadata_i' : word `metadata_i' of `varlist'
        if "`firstrow'" == "varlabels" {
            local header_var : word `metadata_i' of `varlist'
            local header_label : variable label `header_var'
            if `"`macval(header_label)'"' != "" local __cexport_name_`metadata_i' `"`macval(header_label)'"'
        }
        local __cexport_type_`metadata_i' : word `metadata_i' of `vartypes'
        local __cexport_date_`metadata_i' : word `metadata_i' of `date_cols'
        if "`__cexport_date_`metadata_i''" == "" local __cexport_date_`metadata_i' 0
    }
    local __cexport_filename `"`using'"'
    local __cexport_filename_len = strlen(`"`__cexport_filename'"')
    local __cexport_sheet `"`sheet'"'
    local __cexport_sheet_len = strlen(`"`__cexport_sheet'"')
    local __cexport_missing `"`missing'"'
    local __cexport_missing_len = strlen(`"`__cexport_missing'"')
    local opt_replace = cond("`replace'" != "", "replace", "")

    * Record start time
    local __ct_elapsed99 = 0
    if "`__ct_elapsed99'" == "" local __ct_elapsed99 = 0
    quietly _ctools_clock __ct_start99

    * Set string width metadata for flat buffer optimization
    _ctools_strw `export_varlist'

    * Stata answers an if one observation at a time. Without one the plugin
    * skips the check; an if is marked first and passed last, as a sample
    * marker the plugin reads in parallel, unless in limits the range
    * (marking covers every observation). The marker is the last variable
    * until it is dropped after the call, which is then free.
    local opt_select "skipif"
    local marker ""
    local ifcond `"`if'"'
    if `"`if'"' != "" & `"`in'"' == "" {
        tempvar marker
        mark `marker' `if'
        local opt_select "touse"
        local ifcond ""
    }
    else if `"`if'"' != "" {
        local opt_select ""
    }

    * Call the C plugin
    * Plugin expects options only; paths/metadata are length-checked locals.
    * Use export_varlist (may contain decoded temp vars for value labels)
    capture noisily plugin call ctools_plugin `export_varlist' `marker' `ifcond' `in', ///
        "cexport `threads_code' `plugin_delim' `opt_replace' `opt_noheader' `opt_quote' `opt_noquoteif' `opt_verbose' `opt_mmap' `opt_nofsync' `opt_direct' `opt_prefault' `opt_crlf' `opt_noparallel' `opt_select'"

    local export_rc = _rc
    if "`marker'" != "" drop `marker'

    * Clean up global macros

    if `export_rc' {
        di as error "Error exporting data (rc=`export_rc')"
        exit `export_rc'
    }

    quietly _ctools_clock __ct_now

    local __ct_elapsed99 = `__ct_elapsed99' + (`__ct_now' - `__ct_start99')
    * Elapsed seconds are held in caller-local timing state.
    local elapsed = `__ct_elapsed99'

    * Display summary
    di as text ""
    di as text "file " as result `"`using'"' as text " saved"
    di as text "(" as result %12.0fc `nobs' as text " observations written)"

    * Display timing if requested
    if "`verbose'" != "" {
        capture local __time_load = _cexport_time_load
        if _rc != 0 local __time_load = .
        capture local __time_format = _cexport_time_format
        if _rc != 0 local __time_format = .
        capture local __time_write = _cexport_time_write
        if _rc != 0 local __time_write = .
        capture local __time_total = _cexport_time_total
        if _rc != 0 local __time_total = .

        if `__time_total' != . {
            local plugin_overhead = `elapsed' - `__time_total'
            if `plugin_overhead' < 0 local plugin_overhead = 0
        }
        else {
            local plugin_overhead = .
        }
        di as text ""
        di as text "{hline 55}"
        di as text "cexport timing breakdown:"
        di as text "{hline 55}"
        di as text "  C plugin internals:"
        di as text "    Data load:              " as result %8.4f `__time_load' " sec"
        di as text "    Format:                 " as result %8.4f `__time_format' " sec"
        di as text "    Write to file:          " as result %8.4f `__time_write' " sec"
        di as text "  {hline 53}"
        di as text "    C plugin total:         " as result %8.4f `__time_total' " sec"
        di as text ""
        di as text "  Stata overhead:"
        di as text "    Plugin call overhead:   " as result %8.4f `plugin_overhead' " sec"
        di as text "  {hline 53}"
        di as text "    Stata overhead total:   " as result %8.4f `plugin_overhead' " sec"
        di as text "{hline 55}"
        di as text "    Wall clock total:       " as result %8.4f `elapsed' " sec"
        di as text "{hline 55}"
        if `elapsed' > 0 {
            local rows_per_sec = `nobs' / `elapsed'
            di as text "    Throughput:             " as result %12.0fc `rows_per_sec' as text " rows/sec"
        }

        * Display thread diagnostics
        capture local __threads_max = _cexport_threads_max
        if _rc == 0 {
            capture local __openmp_enabled = _cexport_openmp_enabled
            if _rc != 0 local __openmp_enabled = 0
            di as text ""
            di as text "  Thread diagnostics:"
            di as text "    OpenMP enabled:         " as result %8.0f `__openmp_enabled'
            di as text "    Max threads available:  " as result %8.0f `__threads_max'
            di as text "{hline 55}"
        }
    }

    * Return results
    return scalar N = `nobs'
    return scalar k = `nvars'
    return scalar time = `elapsed'
    return local filename `"`using'"'

    local __ct_elapsed99 = 0
end

/*******************************************************************************
 * cexport_excel: Export to Excel (.xlsx) files
 *
 * Syntax: cexport excel [varlist] [using] filename [if] [in], [options]
 *
 * Options:
 *   sheet(name)    - Worksheet name (default: "Sheet1")
 *   firstrow(variables|nonames) - First row handling
 *   replace        - Overwrite existing file
 *   nolabel        - Export numeric values instead of value labels
 *   verbose        - Display timing information
 ******************************************************************************/
program define cexport_excel, rclass
    version 14.1

    * Check observation limit (Stata plugin API limitation)
    if _N > 2147483647 {
        di as error "ctools does not support datasets exceeding 2^31 (2.147 billion) observations"
        di as error "This is a limitation of Stata's plugin API"
        exit 920
    }

    * Support both "using filename" and just "filename" (like export excel does)
    syntax [anything] [using/] [if] [in], [SHEET(string asis) FIRSTrow(string) ///
        REPLACE DATAfmt DATEString(string) NOLabel Verbose ///
        CELL(string) MISSING(string) KEEPCELLfmt THReads(integer 0) ///
        SHEETMODify SHEETREPlace LOCALE(string)]

    _cexport_excel_sheet `macval(sheet)'
    local sheet `"`r(sheet)'"'
    local sheet_action `r(action)'
    if "`sheetmodify'" != "" {
        if "`sheet_action'" == "sheetreplace" exit 198
        local sheet_action "sheetmodify"
    }
    if "`sheetreplace'" != "" {
        if "`sheet_action'" == "sheetmodify" exit 198
        local sheet_action "sheetreplace"
    }
    if "`sheet_action'" != "" & "`replace'" != "" {
        di as error "sheet modification or replacement cannot be combined with replace"
        exit 198
    }

    * Handle filename - can come from using/ or as last positional argument
    if `"`using'"' == "" & `"`anything'"' != "" {
        local __tokens `"`anything'"'
        local __filename ""
        local __varlist ""
        while `"`__tokens'"' != "" {
            gettoken __tok __tokens : __tokens
            if `"`__tokens'"' == "" local __filename `"`__tok'"'
            else {
                local __varlist `"`__varlist' `__tok'"'
            }
        }
        if `"`__filename'"' == "" {
            di as error "cexport excel: filename required"
            di as error "Syntax: cexport excel [varlist] [using] filename [, options]"
            exit 198
        }
        local using `"`__filename'"'
        local anything `"`__varlist'"'
    }
    if `"`using'"' == "" {
        di as error "cexport excel: filename required"
        di as error "Syntax: cexport excel [varlist] [using] filename [, options]"
        exit 198
    }
    * Resolve varlist from anything.
    * Must happen BEFORE marksample, which creates a touse tempvar
    * that ds would include in the variable list.
    if strtrim(`"`anything'"') != "" {
        unab varlist : `anything'
    }
    else {
        qui ds
        local varlist `r(varlist)'
    }

    * Mark sample
    marksample touse, novarlist

    * Validate cell option format (e.g., A1, B5, AA10)
    if `"`cell'"' != "" {
        local cell_upper = upper(`"`cell'"')
        * Check format: 1-3 letters followed by 1 or more digits
        if !regexm("`cell_upper'", "^[A-Z]+[0-9]+$") {
            di as error "cexport excel: cell() must be a valid cell reference (e.g., A1, B5)"
            exit 198
        }
        local cell `"`cell_upper'"'
    }

    * Native export assumes .xlsx when no Excel extension is supplied.
    if !inlist(lower(substr(`"`using'"',-4,4)),".xls") & lower(substr(`"`using'"',-5,5)) != ".xlsx" {
        local using `"`using'.xlsx"'
    }
    * Validate file extension
    local ext = substr(lower(`"`using'"'), -5, 5)
    local excel_engine "cexport_xlsx"
    if lower(substr(`"`using'"',-4,4)) == ".xls" local excel_engine "cexport_xls"
    if "`ext'" != ".xlsx" & "`excel_engine'" != "cexport_xls" {
        di as error "cexport excel: file must have .xls or .xlsx extension"
        exit 198
    }

    * Parse firstrow option
    local opt_firstrow = "nofirstrow"
    if "`firstrow'" != "" & substr("variables",1,strlen("`firstrow'")) == "`firstrow'" local firstrow "variables"
    if strlen("`firstrow'") >= 4 & substr("varlabels",1,strlen("`firstrow'")) == "`firstrow'" local firstrow "varlabels"
    if "`firstrow'" != "" {
        if "`firstrow'" == "nonames" {
            local opt_firstrow = "nofirstrow"
        }
        else if inlist("`firstrow'", "variables", "varlabels") {
            local opt_firstrow "firstrow"
        }
        else {
            di as error "cexport excel: firstrow() must be 'variables' or 'nonames'"
            exit 198
        }
    }

    * Handle value labels
    local export_varlist ""
    local decoded_vars ""
    if "`nolabel'" == "" {
        foreach var of local varlist {
            local vallbl : value label `var'
            if "`vallbl'" != "" {
                tempvar decoded_`var'
                qui decode `var', gen(`decoded_`var'')
                qui recast str2045 `decoded_`var''
                * Unlabeled values, extended missing values included (.b), are
                * written as numbers as native export excel does; only system
                * missing is left empty
                qui replace `decoded_`var'' = string(`var',"%18.0g") if `decoded_`var''=="" & `var' != .
                local export_varlist `export_varlist' `decoded_`var''
                local decoded_vars `decoded_vars' `decoded_`var''
            }
            else {
                local export_varlist `export_varlist' `var'
            }
        }
    }
    else {
        local export_varlist `varlist'
    }

    * Handle datafmt and datestring(): format date/time variables as strings
    if "`datafmt'" != "" | `"`datestring'"' != "" {
        local new_export_varlist ""
        local formatted_vars ""
        local export_idx = 0
        foreach var of local export_varlist {
            local export_idx = `export_idx' + 1
            * Get original variable name for format lookup
            local origvar : word `export_idx' of `varlist'

            * Check if this is a date/time variable by looking at its format
            local fmt : format `origvar'
            local is_date_fmt = 0
            if substr("`fmt'", 1, 2) == "%t" | substr("`fmt'", 1, 3) == "%-t" {
                local is_date_fmt = 1
            }

            if `is_date_fmt' {
                * This is a date/time variable - convert to formatted string
                tempvar fmtvar_`export_idx'

                * Use datestring format if specified, otherwise use variable's display format
                * Note: missing values should become empty strings (like Stata's behavior)
                if `"`datestring'"' != "" {
                    qui gen str `fmtvar_`export_idx'' = cond(missing(`origvar'), "", string(`origvar', `"`datestring'"'))
                }
                else {
                    qui gen str `fmtvar_`export_idx'' = cond(missing(`origvar'), "", string(`origvar', "`fmt'"))
                }

                local new_export_varlist `new_export_varlist' `fmtvar_`export_idx''
                local formatted_vars `formatted_vars' `fmtvar_`export_idx''
            }
            else {
                * Not a date variable - keep as is
                local new_export_varlist `new_export_varlist' `var'
            }
        }
        local export_varlist `new_export_varlist'
    }
    else {
        * No datafmt/datestring: convert date values to Excel serial numbers
        * so they are stored as native Excel dates (not strings)
        local new_export_varlist ""
        local date_converted_vars ""
        local export_idx = 0
        local has_date_cols = 0
        foreach var of local export_varlist {
            local export_idx = `export_idx' + 1
            local origvar : word `export_idx' of `varlist'
            local fmt : format `origvar'
            local is_date_fmt = 0
            if substr("`fmt'", 1, 2) == "%t" | substr("`fmt'", 1, 3) == "%-t" {
                local is_date_fmt = 1
            }

            if `is_date_fmt' {
                local has_date_cols = 1
                * Determine date type: strip % and optional -
                local fmtsub = substr("`fmt'", 2, .)
                if substr("`fmtsub'", 1, 1) == "-" local fmtsub = substr("`fmtsub'", 2, .)
                local datetype = substr("`fmtsub'", 2, 1)

                tempvar xldate_`export_idx'
                if "`datetype'" == "d" {
                    qui gen double `xldate_`export_idx'' = `origvar' + 21916 if !missing(`origvar')
                }
                else if "`datetype'" == "m" {
                    qui gen double `xldate_`export_idx'' = dofm(`origvar') + 21916 if !missing(`origvar')
                }
                else if "`datetype'" == "q" {
                    qui gen double `xldate_`export_idx'' = dofq(`origvar') + 21916 if !missing(`origvar')
                }
                else if "`datetype'" == "w" {
                    qui gen double `xldate_`export_idx'' = dofw(`origvar') + 21916 if !missing(`origvar')
                }
                else if "`datetype'" == "h" {
                    qui gen double `xldate_`export_idx'' = dofh(`origvar') + 21916 if !missing(`origvar')
                }
                else if "`datetype'" == "y" {
                    qui gen double `xldate_`export_idx'' = dofy(`origvar') + 21916 if !missing(`origvar')
                }
                else if "`datetype'" == "c" | "`datetype'" == "C" {
                    if "`datetype'" == "C" {
                        qui gen double `xldate_`export_idx'' = cofC(`origvar') / 86400000 + 21916 if !missing(`origvar')
                    }
                    else {
                        qui gen double `xldate_`export_idx'' = `origvar' / 86400000 + 21916 if !missing(`origvar')
                    }
                }
                else {
                    qui gen double `xldate_`export_idx'' = `origvar' + 21916 if !missing(`origvar')
                }

                * Excel inserts a nonexistent 29feb1900 at serial 60.
                qui replace `xldate_`export_idx'' = `xldate_`export_idx'' - 1 if `xldate_`export_idx'' < 61
                local new_export_varlist `new_export_varlist' `xldate_`export_idx''
                local date_converted_vars `date_converted_vars' `xldate_`export_idx''
            }
            else {
                local new_export_varlist `new_export_varlist' `var'
            }
        }
        if `has_date_cols' {
            local export_varlist `new_export_varlist'
        }
    }

    * Count variables and observations
    local nvars : word count `varlist'
    qui count `if' `in'
    local nobs = r(N)

    if `nvars' == 0 {
        di as error "cexport excel: no variables to export"
        exit 198
    }

    * Load plugin
    _ctools_load
    * Stata scopes plugin registrations to the calling ado program.
    capture program ctools_plugin, plugin using("`__ctools_plugin'")
    if _rc != 0 & _rc != 110 exit 601
    capture confirm number 0

    * Build plugin arguments
    local opt_replace = cond("`replace'" != "", "replace", "")
    local opt_nolabel = cond("`nolabel'" != "", "nolabel", "")
    local opt_verbose = cond("`verbose'" != "", "verbose", "")
    local opt_cell = cond(`"`cell'"' != "", `"cell=`cell'"', "")
    local opt_keepcellfmt = cond("`keepcellfmt'" != "", "keepcellfmt", "")

    * Pass variable names to plugin


    * Pass variable types
    local vartypes ""
    foreach var of local export_varlist {
        local vtype : type `var'
        if "`vtype'" == "byte" {
            local vartypes `vartypes' 1
        }
        else if "`vtype'" == "int" {
            local vartypes `vartypes' 2
        }
        else if "`vtype'" == "long" {
            local vartypes `vartypes' 3
        }
        else if "`vtype'" == "float" {
            local vartypes `vartypes' 4
        }
        else if "`vtype'" == "double" {
            local vartypes `vartypes' 5
        }
        else {
            * String
            local vartypes `vartypes' 0
        }
    }


    * Build date column flags for plugin
    local date_cols ""
    local export_idx = 0
    foreach var of local export_varlist {
        local export_idx = `export_idx' + 1
        local origvar : word `export_idx' of `varlist'
        local fmt : format `origvar'
        local is_date = 0
        if substr("`fmt'", 1, 2) == "%t" | substr("`fmt'", 1, 3) == "%-t" {
            local is_date = 1
            if strpos("`fmt'", "tc") | strpos("`fmt'", "tC") local is_date = 2
            capture confirm numeric variable `var'
            if _rc local is_date = 0
        }
        local date_cols `date_cols' `is_date'
    }


    * Each metadata field has an independent local; no aggregate buffer limit.
    local metadata_count : word count `varlist'
    forvalues metadata_i=1/`metadata_count' {
        local __cexport_name_`metadata_i' : word `metadata_i' of `varlist'
        if "`firstrow'" == "varlabels" {
            local header_var : word `metadata_i' of `varlist'
            local header_label : variable label `header_var'
            if `"`macval(header_label)'"' != "" local __cexport_name_`metadata_i' `"`macval(header_label)'"'
        }
        local __cexport_type_`metadata_i' : word `metadata_i' of `vartypes'
        local __cexport_date_`metadata_i' : word `metadata_i' of `date_cols'
        if "`__cexport_date_`metadata_i''" == "" local __cexport_date_`metadata_i' 0
    }
    local __cexport_filename `"`using'"'
    local __cexport_filename_len = strlen(`"`__cexport_filename'"')
    local __cexport_sheet `"`sheet'"'
    local __cexport_sheet_len = strlen(`"`__cexport_sheet'"')
    local __cexport_missing `"`missing'"'
    local __cexport_missing_len = strlen(`"`__cexport_missing'"')
    local opt_replace = cond("`replace'" != "", "replace", "")

    * Record start time
    local __ct_elapsed99 = 0
    if "`__ct_elapsed99'" == "" local __ct_elapsed99 = 0
    quietly _ctools_clock __ct_start99

    * Set string width metadata for flat buffer optimization
    _ctools_strw `export_varlist'

    local threads_code ""
    if `threads' > 0 local threads_code "threads(`threads')"

    * Call plugin with if `touse' so SF_ifobs() filters correctly
    capture noisily plugin call ctools_plugin `export_varlist' if `touse', ///
        "`excel_engine' `threads_code' `opt_firstrow' `opt_replace' `opt_nolabel' `opt_verbose' `opt_cell' `opt_keepcellfmt' `sheet_action'"

    local export_rc = _rc

    * Clean up

    if `export_rc' {
        di as error "Error exporting XLSX data (rc=`export_rc')"
        exit `export_rc'
    }

    quietly _ctools_clock __ct_now

    local __ct_elapsed99 = `__ct_elapsed99' + (`__ct_now' - `__ct_start99')
    * Elapsed seconds are held in caller-local timing state.
    local elapsed = `__ct_elapsed99'

    * Display summary
    di as text ""
    di as text "file " as result `"`using'"' as text " saved"
    di as text "(" as result %12.0fc `nobs' as text " observations written)"

    if "`verbose'" != "" {
        di as text ""
        di as text "Time: " as result %9.3f `elapsed' as text " seconds"
    }

    * Return results
    return scalar N = `nobs'
    return scalar k = `nvars'
    return scalar time = `elapsed'
    return local filename `"`using'"'

    local __ct_elapsed99 = 0
end

* Parse the nested native sheet(name, modify|replace) syntax independently.
program define _cexport_excel_sheet, rclass
    version 14.1
    syntax [anything(name=sheet)] [, MODify REPlace]
    if "`modify'" != "" & "`replace'" != "" exit 198
    local sheet = strtrim(`"`macval(sheet)'"')
    if substr(`"`macval(sheet)'"',1,1) == char(34) {
        gettoken sheet rest : sheet
        if strtrim(`"`rest'"') != "" exit 198
    }
    return local sheet `"`macval(sheet)'"'
    if "`modify'" != "" return local action "sheetmodify"
    else if "`replace'" != "" return local action "sheetreplace"
    else return local action ""
end