282 lines
8.4 KiB
Go
282 lines
8.4 KiB
Go
package zoptions
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import (
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"io"
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"os"
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"time"
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)
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type NotifyParameters struct {
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// AlwaysSend makes sure this message when set to true
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// is always sent no matter the condition.
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//
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// It will cause `zen` to ignore every other
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// parameters and just send the message.
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AlwaysSend bool
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// InitialBackoff is the starting backoff.
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//
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// If not specified, the default duration is time.Minute.
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InitialBackoff time.Duration
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// MaxBackoff is the maximum backoff. If unset, the default value
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// is time.Hour * 24.
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MaxBackoff time.Duration
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// BackoffFormula is a string that represents the formula to calculate the backoff time
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// when multiple message with the same key is fired off repeatedly.
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//
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// It uses CEL (Common Expression Language) syntax. See: https://github.com/google/cel-go
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// for the language spec.
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//
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// Expression must return a duration type.
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//
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// If invalid cel expression, empty string, or wrong return value, default formula will be used.
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//
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// Available variables:
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//
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// - `repeat`: the number of times the notification has been sent. type: int.
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// - `last`: the last time the notification was sent. type: timestamp.
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// - `prev_backoff`: the backoff value from previous evaluation. 0 if first seen. Type: duration.
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// - `initial_backoff`: the initial_backoff value. Type: duration
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// - `max_backoff`: the maximum backoff value. Type: duration
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//
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// Available Non-Standard functions:
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//
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// // pow multiplies the base with the exponent
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// pow(base: double, exp: double) -> double
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//
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// // mult_dur_double multiplies the duration with the double value
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// mult_dur_double(dur: duration, mult: double) -> duration
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//
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//
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// Example (and also default formula):
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//
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// mult_dur_double(initial_backoff, pow(1.5, double(repeat))) > max_backoff
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// ? max_backoff
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// : mult_dur_double(initial_backoff, pow(1.5, double(repeat)))
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BackoffFormula string
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// Attachments is a list of NamedReader (files or buffer) that will be sent as attachments.
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//
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// Attachments are guaranteed to be closed wether the notification is sent successfully or not
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// to avoid resource leaks.
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Attachments []NamedReader
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}
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type NotifyOption interface {
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Apply(parameters *NotifyParameters)
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}
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// NotifyOptionFunc is a shortcut to create a NotifyOption from a function.
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type NotifyOptionFunc func(parameters *NotifyParameters)
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func (f NotifyOptionFunc) Apply(parameters *NotifyParameters) {
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f(parameters)
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}
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type NotifiyOptionBuilder []NotifyOption
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func (no NotifiyOptionBuilder) Apply(parameters *NotifyParameters) {
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for _, opt := range no {
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opt.Apply(parameters)
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}
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}
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// AlwaysSend makes sure this message when set to true
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// is always sent no matter the condition.
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//
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// It will cause `zen` to ignore every other
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// parameters and just send the message.
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func (no NotifiyOptionBuilder) AlwaysSend(alwaysSend bool) NotifiyOptionBuilder {
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return append(no, NotifyOptionFunc(func(parameters *NotifyParameters) {
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parameters.AlwaysSend = alwaysSend
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}))
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}
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// InitialBackoff is the starting backoff.
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//
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// If not specified, the default duration is time.Minute.
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func (no NotifiyOptionBuilder) InitialBackoff(backoff time.Duration) NotifiyOptionBuilder {
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return append(no, NotifyOptionFunc(func(parameters *NotifyParameters) {
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parameters.InitialBackoff = backoff
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}))
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}
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// MaxBackoff is the maximum backoff. If unset, the default value
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// is time.Hour * 24.
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func (no NotifiyOptionBuilder) MaxBackoff(maxBackoff time.Duration) NotifiyOptionBuilder {
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return append(no, NotifyOptionFunc(func(parameters *NotifyParameters) {
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parameters.MaxBackoff = maxBackoff
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}))
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}
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// Attachments is a list attachments (files or buffers) that will be sent with the notification.
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//
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// Attachments are guaranteed to be closed wether the notification is sent successfully or not
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// to avoid resource leaks.
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func (no NotifiyOptionBuilder) Attachments(attachments ...NamedReader) NotifiyOptionBuilder {
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return append(no, NotifyOptionFunc(func(parameters *NotifyParameters) {
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parameters.Attachments = append(parameters.Attachments, attachments...)
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}))
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}
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// BackoffFormula is a string that represents the formula to calculate the backoff time
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// when multiple message with the same key is fired off repeatedly.
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//
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// It uses CEL (Common Expression Language) syntax. See: https://github.com/google/cel-go
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// for the language spec.
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//
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// Expression must return a duration type.
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//
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// If invalid cel expression, empty string, or wrong return value, default formula will be used.
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//
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// Available variables:
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//
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// - `repeat`: the number of times the notification has been sent. type: int.
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// - `last`: the last time the notification was sent. type: timestamp.
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// - `prev_backoff`: the backoff value from previous evaluation. 0 if this message is first seen. Type: duration.
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// - `initial_backoff`: the initial_backoff value. Type: duration
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// - `max_backoff`: the maximum backoff value. Type: duration
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//
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// Available Non-Standard functions:
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//
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// // pow multiplies the base with the exponent
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// pow(base: double, exp: double) -> double
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//
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// // mult_dur_double multiplies the duration with the double value
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// mult_dur_double(dur: duration, mult: double) -> duration
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//
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// Example (and also default formula):
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//
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// mult_dur_double(initial_backoff, pow(1.5, double(repeat))) > max_backoff
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// ? max_backoff
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// : mult_dur_double(initial_backoff, pow(1.5, double(repeat)))
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func (no NotifiyOptionBuilder) BackoffFormula(formula string) NotifiyOptionBuilder {
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return append(no, NotifyOptionFunc(func(parameters *NotifyParameters) {
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parameters.BackoffFormula = formula
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}))
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}
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func Notify() NotifiyOptionBuilder {
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return NotifiyOptionBuilder{}
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}
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// NamedReader is an interface that extends io.ReadCloser with
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// Filename and MimeType methods.
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//
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// This is used to pass a file with its metadata to the notification
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// system.
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type NamedReader interface {
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io.ReadCloser
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// Filename returns the name of the file.
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//
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// Filename will be sluggified and used as the filename
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// in the notification.
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Filename() string
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// MimeType returns the mime type of the file.
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//
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// MimeType is used by Zen to determine the type of the file.
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//
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// Use constant values from: https://github.com/ldez/mimetype
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// for maximum compatibility.
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//
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// Attachment like images, videos, etc, using well known mime types
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// that are supported by browsers can
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// be displayed by the browser.
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//
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// Mimetypes that are supported by browsers:
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//
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// - image/png
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// - image/jpeg
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// - image/gif
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// - image/svg+xml
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// - video/mp4
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// - video/webm
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// - video/ogg
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// - audio/mpeg
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// - audio/ogg
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// - audio/wav
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//
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// Documents like pdf, docx, xlsx, will be given a download link and proper icons.
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// How they are handled is up to the browser.
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//
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// If the mimetype is not supported, it will be given a download link with a generic icon.
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MimeType() string
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}
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// NewNamedReader creates a new NamedReader from the given filename, mimeType and reader.
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//
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// If reader implements io.Closer, it will be closed when the NamedReader is closed.
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//
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// Otherwise, the reader will be wrapped with io.NopCloser.
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func NewNamedReader(filename, mimeType string, reader io.Reader) NamedReader {
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var rc io.ReadCloser
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if c, ok := reader.(io.ReadCloser); ok {
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rc = c
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} else {
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rc = io.NopCloser(reader)
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}
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return &namedReader{
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filename: filename,
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mimeType: mimeType,
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reader: rc,
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}
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}
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// NewNamedReaderFromFile same as NewNamedReader but reads the file from the filesystem.
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//
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// If the file does not exist or there is an error in permissions on reading the file,
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// the error will be logged but otherwise ignored.
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//
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// Example:
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//
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// NewNamedReaderFromFile("path/to/file.txt", "text/plain")
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func NewNamedReaderFromFile(path string, mimetype string) NamedReader {
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var rc io.ReadCloser
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f, err := os.Open(path)
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if err != nil {
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rc = &errorReader{err}
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} else {
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rc = f
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}
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return &namedReader{
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filename: path,
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mimeType: mimetype,
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reader: rc,
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}
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}
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type namedReader struct {
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filename string
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mimeType string
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reader io.ReadCloser
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}
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func (na *namedReader) Read(p []byte) (n int, err error) {
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return na.reader.Read(p)
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}
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func (na *namedReader) Close() error {
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return na.reader.Close()
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}
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func (na *namedReader) Filename() string {
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return na.filename
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}
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func (na *namedReader) MimeType() string {
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return na.mimeType
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}
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type errorReader struct {
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err error
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}
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func (er *errorReader) Read(p []byte) (n int, err error) {
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return 0, er.err
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}
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func (er *errorReader) Close() error {
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return nil
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}
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