package buildfile

import (
	"bytes"
	"fmt"
)

type Buildfile struct {
	bytes.Buffer
}

func New() *Buildfile {
	b := Buildfile{}
	b.WriteString(base)
	return &b
}

// WriteCmd writes a command to the build file. The
// command will be echoed back as a base16 encoded
// command so that it can be parsed and appended to
// the build output
func (b *Buildfile) WriteCmd(command string) {
	// echo the command as an encoded value
	b.WriteString(fmt.Sprintf("echo '#DRONE:%x'\n", command))
	// and then run the command
	b.WriteString(fmt.Sprintf("%s\n", command))
}

// WriteCmdSilent writes a command to the build file
// but does not echo the command.
func (b *Buildfile) WriteCmdSilent(command string) {
	b.WriteString(fmt.Sprintf("%s\n", command))
}

// WriteComment adds a comment to the build file. This
// is really only used internally for debugging purposes.
func (b *Buildfile) WriteComment(comment string) {
	b.WriteString(fmt.Sprintf("#%s\n", comment))
}

// WriteEnv exports the environment variable as
// part of the script. The environment variables
// are not echoed back to the console, and are
// kept private by default.
func (b *Buildfile) WriteEnv(key, value string) {
	b.WriteString(fmt.Sprintf("export %s=%s\n", key, value))
}

// WriteHost adds an entry to the /etc/hosts file.
func (b *Buildfile) WriteHost(mapping string) {
	b.WriteCmdSilent(fmt.Sprintf("[ -f /usr/bin/sudo ] || echo %q | tee -a /etc/hosts", mapping))
	b.WriteCmdSilent(fmt.Sprintf("[ -f /usr/bin/sudo ] && echo %q | sudo tee -a /etc/hosts", mapping))
}

// every build script starts with the following
// code at the start.
var base = `
#!/bin/bash

# drone configuration files are stored in /etc/drone.d
# execute these files prior to our build to set global
# environment variables and initialize programs (like rbenv)
if [ -d /etc/drone.d ]; then
  for i in /etc/drone.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi

# be sure to exit on error and print out
# our bash commands, so we can which commands
# are executing and troubleshoot failures.
set -e

# user-defined commands below ##############################
`