mirror of
https://github.com/gotenberg/gotenberg.git
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284 lines
8.2 KiB
Go
284 lines
8.2 KiB
Go
package printer
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import (
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"context"
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"fmt"
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"io/ioutil"
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"time"
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"github.com/mafredri/cdp"
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"github.com/mafredri/cdp/devtool"
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"github.com/mafredri/cdp/protocol/network"
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"github.com/mafredri/cdp/protocol/page"
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"github.com/mafredri/cdp/protocol/target"
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"github.com/mafredri/cdp/rpcc"
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"github.com/thecodingmachine/gotenberg/internal/pkg/conf"
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"github.com/thecodingmachine/gotenberg/internal/pkg/xcontext"
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"github.com/thecodingmachine/gotenberg/internal/pkg/xerror"
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"github.com/thecodingmachine/gotenberg/internal/pkg/xlog"
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"github.com/thecodingmachine/gotenberg/internal/pkg/xtime"
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"golang.org/x/sync/errgroup"
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)
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type chromePrinter struct {
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logger xlog.Logger
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url string
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opts ChromePrinterOptions
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}
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// ChromePrinterOptions helps customizing the
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// Google Chrome Printer behaviour.
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type ChromePrinterOptions struct {
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WaitTimeout float64
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WaitDelay float64
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HeaderHTML string
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FooterHTML string
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PaperWidth float64
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PaperHeight float64
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MarginTop float64
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MarginBottom float64
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MarginLeft float64
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MarginRight float64
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Landscape bool
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}
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// DefaultChromePrinterOptions returns the default
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// Google Chrome Printer options.
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func DefaultChromePrinterOptions(config conf.Config) ChromePrinterOptions {
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const defaultHeaderFooterHTML string = "<html><head></head><body></body></html>"
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return ChromePrinterOptions{
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WaitTimeout: config.DefaultWaitTimeout(),
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WaitDelay: 0.0,
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HeaderHTML: defaultHeaderFooterHTML,
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FooterHTML: defaultHeaderFooterHTML,
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PaperWidth: 8.27,
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PaperHeight: 11.7,
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MarginTop: 1.0,
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MarginBottom: 1.0,
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MarginLeft: 1.0,
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MarginRight: 1.0,
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Landscape: false,
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}
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}
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func (p chromePrinter) Print(destination string) error {
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const op string = "printer.chromePrinter.Print"
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logOptions(p.logger, p.opts)
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ctx, cancel := xcontext.WithTimeout(p.logger, p.opts.WaitTimeout+p.opts.WaitDelay)
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defer cancel()
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resolver := func() error {
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devt, err := devtool.New("http://localhost:9222").Version(ctx)
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if err != nil {
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return err
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}
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// connect to WebSocket URL (page) that speaks the Chrome DevTools Protocol.
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devtConn, err := rpcc.DialContext(ctx, devt.WebSocketDebuggerURL)
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if err != nil {
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return err
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}
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defer devtConn.Close() // nolint: errcheck
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// create a new CDP Client that uses conn.
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devtClient := cdp.NewClient(devtConn)
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newContextTarget, err := devtClient.Target.CreateBrowserContext(ctx)
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if err != nil {
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return err
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}
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/*
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close the browser context when done.
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we're not using the "default" context
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as it may timeout before actually closing
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the browser context.
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see: https://github.com/mafredri/cdp/issues/101#issuecomment-524533670
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*/
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disposeBrowserContextArgs := target.NewDisposeBrowserContextArgs(newContextTarget.BrowserContextID)
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defer devtClient.Target.DisposeBrowserContext(context.Background(), disposeBrowserContextArgs) // nolint: errcheck
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// create a new blank target with the new browser context.
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createTargetArgs := target.
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NewCreateTargetArgs("about:blank").
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SetBrowserContextID(newContextTarget.BrowserContextID)
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newTarget, err := devtClient.Target.CreateTarget(ctx, createTargetArgs)
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if err != nil {
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return err
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}
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// connect the client to the new target.
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newTargetWsURL := fmt.Sprintf("ws://127.0.0.1:9222/devtools/page/%s", newTarget.TargetID)
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newContextConn, err := rpcc.DialContext(ctx, newTargetWsURL)
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if err != nil {
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return err
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}
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defer newContextConn.Close() // nolint: errcheck
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// create a new CDP Client that uses newContextConn.
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targetClient := cdp.NewClient(newContextConn)
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closeTargetArgs := target.NewCloseTargetArgs(newTarget.TargetID)
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/*
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close the target when done.
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we're not using the "default" context
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as it may timeout before actually closing
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the target.
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see: https://github.com/mafredri/cdp/issues/101#issuecomment-524533670
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*/
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defer targetClient.Target.CloseTarget(context.Background(), closeTargetArgs) // nolint: errcheck
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// enable all events.
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if err := p.enableEvents(ctx, targetClient); err != nil {
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return err
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}
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// listen for all events.
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if err := p.listenEvents(ctx, targetClient); err != nil {
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return err
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}
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// apply a wait delay (if any).
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if p.opts.WaitDelay > 0.0 {
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// wait for a given amount of time (useful for javascript delay).
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p.logger.DebugfOp(op, "applying a wait delay of '%.2fs'...", p.opts.WaitDelay)
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time.Sleep(xtime.Duration(p.opts.WaitDelay))
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} else {
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p.logger.DebugOp(op, "no wait delay to apply, moving on...")
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}
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// print the page to PDF.
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print, err := targetClient.Page.PrintToPDF(
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ctx,
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page.NewPrintToPDFArgs().
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SetPaperWidth(p.opts.PaperWidth).
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SetPaperHeight(p.opts.PaperHeight).
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SetMarginTop(p.opts.MarginTop).
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SetMarginBottom(p.opts.MarginBottom).
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SetMarginLeft(p.opts.MarginLeft).
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SetMarginRight(p.opts.MarginRight).
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SetLandscape(p.opts.Landscape).
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SetDisplayHeaderFooter(true).
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SetHeaderTemplate(p.opts.HeaderHTML).
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SetFooterTemplate(p.opts.FooterHTML).
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SetPrintBackground(true),
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)
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if err != nil {
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return err
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}
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if err := ioutil.WriteFile(destination, print.Data, 0644); err != nil {
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return err
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}
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return nil
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}
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if err := resolver(); err != nil {
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return xcontext.MustHandleError(
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ctx,
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xerror.New(op, err),
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)
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}
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return nil
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}
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func (p chromePrinter) enableEvents(ctx context.Context, client *cdp.Client) error {
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const op string = "printer.chromePrinter.enableEvents"
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// enable all the domain events that we're interested in.
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if err := runBatch(
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func() error { return client.DOM.Enable(ctx) },
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func() error { return client.Network.Enable(ctx, network.NewEnableArgs()) },
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func() error { return client.Page.Enable(ctx) },
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func() error {
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return client.Page.SetLifecycleEventsEnabled(ctx, page.NewSetLifecycleEventsEnabledArgs(true))
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},
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func() error { return client.Runtime.Enable(ctx) },
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); err != nil {
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return xerror.New(op, err)
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}
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return nil
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}
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func (p chromePrinter) listenEvents(ctx context.Context, client *cdp.Client) error {
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const op string = "printer.chromePrinter.listenEvents"
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resolver := func() error {
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// make sure Page events are enabled.
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if err := client.Page.Enable(ctx); err != nil {
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return err
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}
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// make sure Network events are enabled.
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if err := client.Network.Enable(ctx, nil); err != nil {
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return err
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}
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// create all clients for events.
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domContentEventFired, err := client.Page.DOMContentEventFired(ctx)
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if err != nil {
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return err
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}
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defer domContentEventFired.Close() // nolint: errcheck
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loadEventFired, err := client.Page.LoadEventFired(ctx)
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if err != nil {
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return err
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}
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defer loadEventFired.Close() // nolint: errcheck
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lifecycleEvent, err := client.Page.LifecycleEvent(ctx)
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if err != nil {
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return err
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}
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defer lifecycleEvent.Close() // nolint: errcheck
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loadingFinished, err := client.Network.LoadingFinished(ctx)
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if err != nil {
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return err
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}
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defer loadingFinished.Close() // nolint: errcheck
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if _, err := client.Page.Navigate(ctx, page.NewNavigateArgs(p.url)); err != nil {
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return err
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}
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// wait for all events.
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return runBatch(
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func() error {
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_, err := domContentEventFired.Recv()
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if err != nil {
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return err
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}
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p.logger.DebugOp(op, "event 'domContentEventFired' received")
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return nil
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},
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func() error {
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_, err := loadEventFired.Recv()
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if err != nil {
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return err
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}
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p.logger.DebugOp(op, "event 'loadEventFired' received")
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return nil
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},
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func() error {
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const networkIdleEventName string = "networkIdle"
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for {
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ev, err := lifecycleEvent.Recv()
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if err != nil {
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return err
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}
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p.logger.DebugfOp(op, "event '%s' received", ev.Name)
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if ev.Name == networkIdleEventName {
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break
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}
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}
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return nil
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},
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func() error {
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_, err := loadingFinished.Recv()
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if err != nil {
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return err
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}
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p.logger.DebugOp(op, "event 'loadingFinished' received")
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return nil
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},
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)
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}
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if err := resolver(); err != nil {
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return xerror.New(op, err)
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}
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return nil
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}
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func runBatch(fn ...func() error) error {
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// run all functions simultaneously and wait until
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// execution has completed or an error is encountered.
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eg := errgroup.Group{}
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for _, f := range fn {
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eg.Go(f)
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}
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return eg.Wait()
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}
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// Compile-time checks to ensure type implements desired interfaces.
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var (
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_ = Printer(new(chromePrinter))
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)
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