<?php
/*
 * This script takes two files, an IServ user export CSV and a DiViS student <> parents CSV
 * and maps the parents to the IServ students, creating a third CSV file that can be imported
 * into the IServ Elternverwaltung module.
 * 
 * The IServ user export CSV is expected to have the following columns:
 * Account;Vorname;Nachname;Status;"Erstellt am";"Erstellt von";"Interne ID";Benutzertyp;Import-ID;Klasse/Information;E-Mail-Adresse;Gruppen
 *
 * The student <> parents mapped CSV from DiViS should have the following columns:
 * "Schüler Vorname","Schüler Nachname","Eltern 1 Vorname","Eltern 1 Nachname","Eltern 2 Vorname","Eltern 2 Nachname"
 * 
 * The CSV exported by this script will have the following columns:
 * Nachname;Vorname;Kind-ID;Klasse
 * 
 * Status messages, information and errors are always written to STDERR, while the generated CSV
 * will be exported to STDOUT, meaning you can redirect the STDOUT output of this script to a file
 * to export the CSV and still be able to read any informational messages:
 * $ php ./IServ_Elternimport_Divis.php iserv-user-export.csv divis-parents-export.csv > Parents_Import.csv
 */

define ("MIN_NAME_MATCHING_PERCENTAGE", 85);
define ("WRITE_TO_CONSOLE", true);
define ("IS_CLI", (php_sapi_name() == "cli"));

/**
 * Writes text to the STDERR stream when running from the command line.
 * 
 * @param  string $text The text to write to console
 * @return void
 */
function console_write ($text) {
    global $argv;
    
    if (IS_CLI && WRITE_TO_CONSOLE) {
        fwrite (STDERR, $text . PHP_EOL);
    }
}

/**
 * Turns the first and last name of a student into a single string
 * used to identify the student in the students array.
 * 
 * @param  string $firstname First name of the student
 * @param  string $lastname  Last name of the student
 * @return string Combined and lower-cased names of the student
 */
function hash_student ($firstname, $lastname) {
    return strtolower($firstname) . "_" . strtolower($lastname);
}

/**
 * Tries the parent(s) of a student by their first and last name
 * in the DiViS student <> parents mapped CSV.
 * 
 * @param  string $firstname First name of the student
 * @param  string $lastname  Last name of the student
 * @return string|null Array of parents first and last names,
 *                     or null if no matching data was found.
 */
function find_parent_by_student ($firstname, $lastname) {
    global $divis_parents;
    
    $student_hash = hash_student ($firstname, $lastname);
    $best_match = [ "match_perc" => 0 ];
    $perc = 0;

    console_write ("INFO: Searching parent(s) for '{$firstname} {$lastname}' ({$student_hash})");

    foreach ($divis_parents as $hash => $parent) {
        similar_text ($student_hash, $hash, $perc);

        // If match is bigger or equal to 85% and this match is higher
        // ranked than the last, make this the current best match
        if (
            $perc >= MIN_NAME_MATCHING_PERCENTAGE &&
            $best_match["match_perc"] < $perc
        ) {
            console_write ("INFO: New best match '{$hash}' at {$perc}%");
            $best_match = [
                "match_perc" => $perc,
                "student_hash" => $student_hash,
                "parent_data" => $parent
            ];
        }
    }

    if ($best_match["match_perc"] == 0) {
        console_write ("WARN: Could not find parent for '{$firstname} {$lastname}'!");
        return null;
    }

    $parent1_firstname = $best_match['parent_data']['parent1_firstname'];
    $parent1_lastname  = $best_match['parent_data']['parent1_lastname'];
    $parent2_firstname = $best_match['parent_data']['parent2_firstname'];
    $parent2_lastname  = $best_match['parent_data']['parent2_lastname'];
    console_write ("INFO: Found parent(s):");
    console_write ("INFO:     First Parent:  {$parent1_firstname} {$parent1_lastname}");
    console_write ("INFO:     Second Parent: {$parent2_firstname} {$parent2_lastname}");

    return [
        "parent1" => [
            "firstname" => $parent1_firstname,
            "lastname"  => $parent1_lastname
        ],
        "parent2" => [
            "firstname" => $parent2_firstname,
            "lastname"  => $parent2_lastname
        ]
    ];
}

// Test if the two required input files have been specified
if (isset ($argc) && $argc == 3) {
    $iserv_infile = $argv[1];
    $divis_infile = $argv[2];

    if (! is_file ($iserv_infile)) {
        console_write ("CRIT: The IServ CSV file specified is not a file or does not exist.");
        exit (1);
    }

    if (! is_file ($divis_infile)) {
        console_write ("CRIT: The DiViS CSV file specified is not a file or does not exist.");
        exit (1);
    }
} else {
    console_write ("Usage: ");
    console_write ("  {$argv[0]} <iserv-user-export.csv> <divis-parents-export.csv>");
    console_write ("");
    exit (1);
}

// Read DiViS student <> parents mapped CSV to an array
$parents_csv_fd = fopen ($divis_infile, "r");
$divis_parents  = [];
while ($parent = fgetcsv ($parents_csv_fd)) {
    $student_firstname = $parent[0];
    $student_lastname  = $parent[1];
    $student_hash = hash_student ($student_firstname, $student_lastname);
    
    $divis_parents[$student_hash] = [
        "student_firstname" => $student_firstname,
        "student_lastname"  => $student_lastname,
        "parent1_firstname" => $parent[2],
        "parent1_lastname"  => $parent[3],
        "parent2_firstname" => $parent[4],
        "parent2_lastname"  => $parent[5]
    ];
}
fclose ($parents_csv_fd);


// Iterate through all students in the IServ student export CSV
$students_csv_fd = fopen ($iserv_infile, "r");
$parents_to_export = [];
$students_without_parents = [];
fgets ($students_csv_fd); // Skip header in the CSV file
while ($student = fgetcsv ($students_csv_fd, null, ";")) {
    // Skip non-student users
    if ($student[7] !== "Schüler") continue;

    $student_firstname = $student[1];
    $student_lastname  = $student[2];
    $student_userid    = $student[8];
    $student_class     = strtolower ($student[9]);
    $student_class     = "klasse." . str_replace (" ", ".", $student_class);

    $parents = find_parent_by_student ($student_firstname, $student_lastname);

    if ($parents == null) {
        $students_without_parents[] = $student;
    } else {
        if ($parents["parent1"]["firstname"] && $parents["parent1"]["lastname"]) {
            $parents_to_export[] = [
                $parents["parent1"]["firstname"],
                $parents["parent1"]["lastname"],
                $student_userid,
                $student_class
            ];
        } else { 
            console_write ("WARN: Parent 1 dataset non-existant for student '{$student_firstname} {$student_lastname}'");
        }

        if ($parents["parent2"]["firstname"] && $parents["parent2"]["lastname"]) {
            $parents_to_export[] = [
                $parents["parent2"]["firstname"],
                $parents["parent2"]["lastname"],
                $student_userid,
                $student_class
            ];
        } else { 
            console_write ("WARN: Parent 2 dataset non-existant for student '{$student_firstname} {$student_lastname}'");
        }
    }

    console_write ("");
}
fclose ($students_csv_fd);

// Iterate through each exportable parent and convert them to a CSV line
if (IS_CLI) {
    $out_fd = STDOUT;
} else {
    $out_fd = fopen ("php://output", "w");
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="Elternimport.csv";');
}

foreach ($parents_to_export as $parent) {
    fputcsv($out_fd, $parent, ";");
}

fclose ($out_fd);
?>