package config

import (
	"fmt"
	"math"
	"time"

	"github.com/dustin/go-humanize"
	"github.com/hashicorp/nomad/helper/pointer"
)

// ArtifactConfig is the configuration specific to the Artifact stanza
type ArtifactConfig struct {
	// HTTPReadTimeout is the duration in which a download must complete or
	// it will be canceled. Defaults to 30m.
	HTTPReadTimeout *string `hcl:"http_read_timeout"`

	// HTTPMaxSize is the maximum size of an artifact that will be downloaded.
	// Defaults to 100GB.
	HTTPMaxSize *string `hcl:"http_max_size"`

	// GCSTimeout is the duration in which a GCS operation must complete or
	// it will be canceled. Defaults to 30m.
	GCSTimeout *string `hcl:"gcs_timeout"`

	// GitTimeout is the duration in which a git operation must complete or
	// it will be canceled. Defaults to 30m.
	GitTimeout *string `hcl:"git_timeout"`

	// HgTimeout is the duration in which an hg operation must complete or
	// it will be canceled. Defaults to 30m.
	HgTimeout *string `hcl:"hg_timeout"`

	// S3Timeout is the duration in which an S3 operation must complete or
	// it will be canceled. Defaults to 30m.
	S3Timeout *string `hcl:"s3_timeout"`

	// DisableFilesystemIsolation will turn off the security feature where the
	// artifact downloader can write only to the task sandbox directory, and can
	// read only from specific locations on the host filesystem.
	DisableFilesystemIsolation *bool `hcl:"disable_filesystem_isolation"`

	// SetEnvironmentVariables is a comma-separated list of environment
	// variable names to inherit from the Nomad Client and set in the artifact
	// download sandbox process.
	SetEnvironmentVariables *string `hcl:"set_environment_variables"`
}

func (a *ArtifactConfig) Copy() *ArtifactConfig {
	if a == nil {
		return nil
	}
	return &ArtifactConfig{
		HTTPReadTimeout:            pointer.Copy(a.HTTPReadTimeout),
		HTTPMaxSize:                pointer.Copy(a.HTTPMaxSize),
		GCSTimeout:                 pointer.Copy(a.GCSTimeout),
		GitTimeout:                 pointer.Copy(a.GitTimeout),
		HgTimeout:                  pointer.Copy(a.HgTimeout),
		S3Timeout:                  pointer.Copy(a.S3Timeout),
		DisableFilesystemIsolation: pointer.Copy(a.DisableFilesystemIsolation),
		SetEnvironmentVariables:    pointer.Copy(a.SetEnvironmentVariables),
	}
}

func (a *ArtifactConfig) Merge(o *ArtifactConfig) *ArtifactConfig {
	switch {
	case a == nil:
		return o.Copy()
	case o == nil:
		return a.Copy()
	default:
		return &ArtifactConfig{
			HTTPReadTimeout:            pointer.Merge(a.HTTPReadTimeout, o.HTTPReadTimeout),
			HTTPMaxSize:                pointer.Merge(a.HTTPMaxSize, o.HTTPMaxSize),
			GCSTimeout:                 pointer.Merge(a.GCSTimeout, o.GCSTimeout),
			GitTimeout:                 pointer.Merge(a.GitTimeout, o.GitTimeout),
			HgTimeout:                  pointer.Merge(a.HgTimeout, o.HgTimeout),
			S3Timeout:                  pointer.Merge(a.S3Timeout, o.S3Timeout),
			DisableFilesystemIsolation: pointer.Merge(a.DisableFilesystemIsolation, o.DisableFilesystemIsolation),
			SetEnvironmentVariables:    pointer.Merge(a.SetEnvironmentVariables, o.SetEnvironmentVariables),
		}
	}
}

func (a *ArtifactConfig) Equal(o *ArtifactConfig) bool {
	if a == nil || o == nil {
		return a == o
	}
	switch {
	case !pointer.Eq(a.HTTPReadTimeout, o.HTTPReadTimeout):
		return false
	case !pointer.Eq(a.HTTPMaxSize, o.HTTPMaxSize):
		return false
	case !pointer.Eq(a.GCSTimeout, o.GCSTimeout):
		return false
	case !pointer.Eq(a.GitTimeout, o.GitTimeout):
		return false
	case !pointer.Eq(a.HgTimeout, o.HgTimeout):
		return false
	case !pointer.Eq(a.S3Timeout, o.S3Timeout):
		return false
	case !pointer.Eq(a.DisableFilesystemIsolation, o.DisableFilesystemIsolation):
		return false
	case !pointer.Eq(a.SetEnvironmentVariables, o.SetEnvironmentVariables):
		return false
	}
	return true
}

func (a *ArtifactConfig) Validate() error {
	if a == nil {
		return fmt.Errorf("artifact must not be nil")
	}

	if a.HTTPReadTimeout == nil {
		return fmt.Errorf("http_read_timeout must be set")
	}
	if v, err := time.ParseDuration(*a.HTTPReadTimeout); err != nil {
		return fmt.Errorf("http_read_timeout not a valid duration: %w", err)
	} else if v < 0 {
		return fmt.Errorf("http_read_timeout must be > 0")
	}

	if a.HTTPMaxSize == nil {
		return fmt.Errorf("http_max_size must be set")
	}
	if v, err := humanize.ParseBytes(*a.HTTPMaxSize); err != nil {
		return fmt.Errorf("http_max_size not a valid size: %w", err)
	} else if v > math.MaxInt64 {
		return fmt.Errorf("http_max_size must be < %d but found %d", int64(math.MaxInt64), v)
	}

	if a.GCSTimeout == nil {
		return fmt.Errorf("gcs_timeout must be set")
	}
	if v, err := time.ParseDuration(*a.GCSTimeout); err != nil {
		return fmt.Errorf("gcs_timeout not a valid duration: %w", err)
	} else if v < 0 {
		return fmt.Errorf("gcs_timeout must be > 0")
	}

	if a.GitTimeout == nil {
		return fmt.Errorf("git_timeout must be set")
	}
	if v, err := time.ParseDuration(*a.GitTimeout); err != nil {
		return fmt.Errorf("git_timeout not a valid duration: %w", err)
	} else if v < 0 {
		return fmt.Errorf("git_timeout must be > 0")
	}

	if a.HgTimeout == nil {
		return fmt.Errorf("hg_timeout must be set")
	}
	if v, err := time.ParseDuration(*a.HgTimeout); err != nil {
		return fmt.Errorf("hg_timeout not a valid duration: %w", err)
	} else if v < 0 {
		return fmt.Errorf("hg_timeout must be > 0")
	}

	if a.S3Timeout == nil {
		return fmt.Errorf("s3_timeout must be set")
	}
	if v, err := time.ParseDuration(*a.S3Timeout); err != nil {
		return fmt.Errorf("s3_timeout not a valid duration: %w", err)
	} else if v < 0 {
		return fmt.Errorf("s3_timeout must be > 0")
	}

	if a.DisableFilesystemIsolation == nil {
		return fmt.Errorf("disable_filesystem_isolation must be set")
	}

	if a.SetEnvironmentVariables == nil {
		return fmt.Errorf("set_environment_variables must be set")
	}

	return nil
}

func DefaultArtifactConfig() *ArtifactConfig {
	return &ArtifactConfig{
		// Read timeout for HTTP operations. Must be long enough to
		// accommodate large/slow downloads.
		HTTPReadTimeout: pointer.Of("30m"),

		// Maximum download size. Must be large enough to accommodate
		// large downloads.
		HTTPMaxSize: pointer.Of("100GB"),

		// Timeout for GCS operations. Must be long enough to
		// accommodate large/slow downloads.
		GCSTimeout: pointer.Of("30m"),

		// Timeout for Git operations. Must be long enough to
		// accommodate large/slow clones.
		GitTimeout: pointer.Of("30m"),

		// Timeout for Hg operations. Must be long enough to
		// accommodate large/slow clones.
		HgTimeout: pointer.Of("30m"),

		// Timeout for S3 operations. Must be long enough to
		// accommodate large/slow downloads.
		S3Timeout: pointer.Of("30m"),

		// Toggle for disabling filesystem isolation, where available.
		DisableFilesystemIsolation: pointer.Of(false),

		// No environment variables are inherited from Client by default.
		SetEnvironmentVariables: pointer.Of(""),
	}
}