134 lines
4.7 KiB
Go
134 lines
4.7 KiB
Go
// Package main is the brother module's Go tools bundle (novox/hq ADR 0464, issue 1440): it scans the glass of a
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// network scanner over eSCL, crops the document, files it as a one-page PDF in a folder and says so on the bus.
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// A scan happens when a tool is called; the module runs no process of its own.
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package main
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import (
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"encoding/json"
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"fmt"
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"os"
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"strings"
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)
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// Settings are the module's seven config values, as the mesh writes them into settings.json (ADR 0348).
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type Settings struct {
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// Scanner is the eSCL base URL, such as http://192.0.2.10/eSCL.
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Scanner string
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// Folder is the absolute path the PDFs are filed in. It is not a manifest resource: a directory's path
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// cannot take a config value (issue 1441), so the code creates it.
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Folder string
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// Resolution is the dpi asked of the scanner: 100, 200, 300 or 600.
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Resolution int
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// ColorMode is "color" or "gray".
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ColorMode string
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// Printer is the device's host (with a port if it is not 443), such as 192.0.2.10: the host of its admin
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// page and its IPP service (ADR 0467 clause 3).
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Printer string
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// PrinterCertificate is the SHA-256 fingerprint of the one certificate the device's admin page may serve.
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PrinterCertificate string
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// Crop says whether the document is cut out of the platen's white.
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Crop bool
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}
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// LoadSettings reads settings.json (the file named by BROTHER_SETTINGS) and lays the defaults under it. A missing
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// or unreadable file is an error that names it; an unset scanner or folder is Missing's to say.
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func LoadSettings(path string) (Settings, error) {
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s := Settings{Resolution: 300, ColorMode: "color", Crop: true}
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if path == "" {
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return s, fmt.Errorf("BROTHER_SETTINGS names no settings file: the module's config does not reach the code")
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}
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raw, err := os.ReadFile(path)
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if err != nil {
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return s, fmt.Errorf("settings cannot be read: %w", err)
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}
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var in map[string]any
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if err := json.Unmarshal(raw, &in); err != nil {
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return s, fmt.Errorf("settings are not JSON (%s): %w", path, err)
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}
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if v, ok := in["scanner"].(string); ok {
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s.Scanner = strings.TrimSpace(v)
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}
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if v, ok := in["scan-folder"].(string); ok {
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s.Folder = strings.TrimSpace(v)
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}
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if v, ok := in["resolution"].(float64); ok && v > 0 {
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s.Resolution = int(v)
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}
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if v, ok := in["color-mode"].(string); ok && v != "" {
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s.ColorMode = v
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}
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if v, ok := in["printer"].(string); ok {
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s.Printer = strings.TrimSpace(v)
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}
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if v, ok := in["printer-certificate"].(string); ok {
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s.PrinterCertificate = strings.TrimSpace(v)
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}
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if v, ok := in["crop"].(bool); ok {
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s.Crop = v
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}
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return s, nil
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}
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// Missing is nil when both required values are set, and otherwise says which is not: no tool writes or
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// asks anything before that (1440/AC7).
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func (s Settings) Missing() error {
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var unset []string
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if s.Scanner == "" {
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unset = append(unset, "scanner")
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}
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if s.Folder == "" {
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unset = append(unset, "scan-folder")
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}
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if len(unset) == 0 {
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return nil
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}
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return fmt.Errorf("config value %s is not set: the operator gives it with the config verb for the brother module on this node",
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strings.Join(unset, " and "))
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}
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// unsetError says which config values are not set.
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func unsetError(names ...string) error {
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return fmt.Errorf("config value %s is not set: the operator gives it with the config verb for the brother module on this node",
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strings.Join(names, " and "))
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}
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// MissingPrinter is nil when the two values the printer's verbs need are set, and otherwise says which is not:
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// nothing is contacted before that (1453/AC4).
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func (s Settings) MissingPrinter() error {
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var unset []string
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if s.Printer == "" {
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unset = append(unset, "printer")
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}
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if s.PrinterCertificate == "" {
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unset = append(unset, "printer-certificate")
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}
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if len(unset) == 0 {
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return nil
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}
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return fmt.Errorf("config value %s is not set: the operator gives it with the config verb for the brother module on this node",
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strings.Join(unset, " and "))
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}
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// bucketFile is the file the mesh writes from the s3-bucket binding (files/bucket.json): the bucket's name and no secret.
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// BucketFile is where the tool side reads brother's bucket from: a file the mesh writes from the s3-bucket binding
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// (files/bucket.json), which holds the bucket's name and no secret.
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type bucketFile struct {
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Bucket string `json:"bucket"`
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}
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// ReadBucket is brother's bucket, as the mesh named it.
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func ReadBucket(path string) (string, error) {
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if path == "" {
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return "", fmt.Errorf("the module was started without the bucket's name (BROTHER_BUCKET)")
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}
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raw, err := os.ReadFile(path)
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if err != nil {
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return "", fmt.Errorf("the bucket's name cannot be read: %w", err)
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}
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var f bucketFile
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if err := json.Unmarshal(raw, &f); err != nil || f.Bucket == "" {
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return "", fmt.Errorf("the bucket file %s names no bucket", path)
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}
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return f.Bucket, nil
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}
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