/* This file is mostly copied over from https://github.com/grafana/agent/tree/main/pkg/integrations/v2/app_agent_receiver,
as soon as we can use agent as a dependency this can be refactored
*/

package frontendlogging

import (
	"fmt"
	"sort"
	"strings"
	"time"

	om "github.com/wk8/go-ordered-map"
	otlp "go.opentelemetry.io/collector/model/otlp"
	otelpdata "go.opentelemetry.io/collector/model/pdata"
)

// KeyVal is an ordered map of string to interface
type KeyVal = om.OrderedMap

// NewKeyVal creates new empty KeyVal
func NewKeyVal() *KeyVal {
	return om.New()
}

func KeyValAdd(kv *KeyVal, key string, value string) {
	if len(value) > 0 {
		kv.Set(key, value)
	}
}

// MergeKeyVal will merge source in target
func MergeKeyVal(target *KeyVal, source *KeyVal) {
	for el := source.Oldest(); el != nil; el = el.Next() {
		target.Set(el.Key, el.Value)
	}
}

// KeyValFromMap will instantiate KeyVal from a map[string]string
func KeyValFromMap(m map[string]string) *KeyVal {
	kv := NewKeyVal()
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, k := range keys {
		KeyValAdd(kv, k, m[k])
	}
	return kv
}

// Payload is the body of the receiver request
type Payload struct {
	Exceptions   []Exception   `json:"exceptions,omitempty"`
	Logs         []Log         `json:"logs,omitempty"`
	Measurements []Measurement `json:"measurements,omitempty"`
	Meta         Meta          `json:"meta,omitempty"`
	Traces       *Traces       `json:"traces,omitempty"`
}

// Frame struct represents a single stacktrace frame
type Frame struct {
	Function string `json:"function,omitempty"`
	Module   string `json:"module,omitempty"`
	Filename string `json:"filename,omitempty"`
	Lineno   int    `json:"lineno,omitempty"`
	Colno    int    `json:"colno,omitempty"`
}

// String function converts a Frame into a human readable string
func (frame Frame) String() string {
	module := ""
	if len(frame.Module) > 0 {
		module = frame.Module + "|"
	}
	return fmt.Sprintf("\n  at %s (%s%s:%v:%v)", frame.Function, module, frame.Filename, frame.Lineno, frame.Colno)
}

// MergeKeyValWithPrefix will merge source in target, adding a prefix to each key being merged in
func MergeKeyValWithPrefix(target *KeyVal, source *KeyVal, prefix string) {
	for el := source.Oldest(); el != nil; el = el.Next() {
		target.Set(fmt.Sprintf("%s%s", prefix, el.Key), el.Value)
	}
}

// Stacktrace is a collection of Frames
type Stacktrace struct {
	Frames []Frame `json:"frames,omitempty"`
}

// Exception struct controls all the data regarding an exception
type Exception struct {
	Type       string       `json:"type,omitempty"`
	Value      string       `json:"value,omitempty"`
	Stacktrace *Stacktrace  `json:"stacktrace,omitempty"`
	Timestamp  time.Time    `json:"timestamp"`
	Trace      TraceContext `json:"trace,omitempty"`
}

// Message string is concatenating of the Exception.Type and Exception.Value
func (e Exception) Message() string {
	return fmt.Sprintf("%s: %s", e.Type, e.Value)
}

// String is the string representation of an Exception
func (e Exception) String() string {
	var stacktrace = e.Message()
	if e.Stacktrace != nil {
		for _, frame := range e.Stacktrace.Frames {
			stacktrace += frame.String()
		}
	}
	return stacktrace
}

// KeyVal representation of the exception object
func (e Exception) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "timestamp", e.Timestamp.String())
	KeyValAdd(kv, "kind", "exception")
	KeyValAdd(kv, "type", e.Type)
	KeyValAdd(kv, "value", e.Value)
	KeyValAdd(kv, "stacktrace", e.String())
	MergeKeyVal(kv, e.Trace.KeyVal())
	return kv
}

// TraceContext holds trace id and span id associated to an entity (log, exception, measurement...).
type TraceContext struct {
	TraceID string `json:"trace_id"`
	SpanID  string `json:"span_id"`
}

// KeyVal representation of the trace context object.
func (tc TraceContext) KeyVal() *KeyVal {
	retv := NewKeyVal()
	KeyValAdd(retv, "traceID", tc.TraceID)
	KeyValAdd(retv, "spanID", tc.SpanID)
	return retv
}

// Traces wraps the otel traces model.
type Traces struct {
	otelpdata.Traces
}

// UnmarshalJSON unmarshals Traces model.
func (t *Traces) UnmarshalJSON(b []byte) error {
	unmarshaler := otlp.NewJSONTracesUnmarshaler()
	td, err := unmarshaler.UnmarshalTraces(b)
	if err != nil {
		return err
	}
	*t = Traces{td}
	return nil
}

// MarshalJSON marshals Traces model to json.
func (t Traces) MarshalJSON() ([]byte, error) {
	marshaler := otlp.NewJSONTracesMarshaler()
	return marshaler.MarshalTraces(t.Traces)
}

// SpanSlice unpacks Traces entity into a slice of Spans.
func (t Traces) SpanSlice() []otelpdata.Span {
	spans := make([]otelpdata.Span, 0)
	rss := t.ResourceSpans()
	for i := 0; i < rss.Len(); i++ {
		rs := rss.At(i)
		ilss := rs.InstrumentationLibrarySpans()
		for j := 0; j < ilss.Len(); j++ {
			s := ilss.At(j).Spans()
			for si := 0; si < s.Len(); si++ {
				spans = append(spans, s.At(si))
			}
		}
	}
	return spans
}

// SpanToKeyVal returns KeyVal representation of a Span.
func SpanToKeyVal(s otelpdata.Span) *KeyVal {
	kv := NewKeyVal()
	if s.StartTimestamp() > 0 {
		KeyValAdd(kv, "timestamp", s.StartTimestamp().AsTime().String())
	}
	if s.EndTimestamp() > 0 {
		KeyValAdd(kv, "end_timestamp", s.StartTimestamp().AsTime().String())
	}
	KeyValAdd(kv, "kind", "span")
	KeyValAdd(kv, "traceID", s.TraceID().HexString())
	KeyValAdd(kv, "spanID", s.SpanID().HexString())
	KeyValAdd(kv, "span_kind", s.Kind().String())
	KeyValAdd(kv, "name", s.Name())
	KeyValAdd(kv, "parent_spanID", s.ParentSpanID().HexString())
	s.Attributes().Range(func(k string, v otelpdata.AttributeValue) bool {
		KeyValAdd(kv, "attr_"+k, fmt.Sprintf("%v", v))
		return true
	})

	return kv
}

// LogLevel is log level enum for incoming app logs
type LogLevel string

const (
	// LogLevelTrace is "trace"
	LogLevelTrace LogLevel = "trace"
	// LogLevelDebug is "debug"
	LogLevelDebug LogLevel = "debug"
	// LogLevelInfo is "info"
	LogLevelInfo LogLevel = "info"
	// LogLevelWarning is "warning"
	LogLevelWarning LogLevel = "warn"
	// LogLevelError is "error"
	LogLevelError LogLevel = "error"
)

// LogContext is a string to string map structure that
// represents the context of a log message
type LogContext map[string]string

// Log struct controls the data that come into a Log message
type Log struct {
	Message   string       `json:"message,omitempty"`
	LogLevel  LogLevel     `json:"level,omitempty"`
	Context   LogContext   `json:"context,omitempty"`
	Timestamp time.Time    `json:"timestamp"`
	Trace     TraceContext `json:"trace,omitempty"`
}

// KeyVal representation of a Log object
func (l Log) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "timestamp", l.Timestamp.String())
	KeyValAdd(kv, "kind", "log")
	KeyValAdd(kv, "message", l.Message)
	KeyValAdd(kv, "level", string(l.LogLevel))
	MergeKeyValWithPrefix(kv, KeyValFromMap(l.Context), "context_")
	MergeKeyVal(kv, l.Trace.KeyVal())
	return kv
}

func (l Log) KeyValContext() *KeyVal {
	kv := NewKeyVal()
	MergeKeyValWithPrefix(kv, KeyValFromMap(l.Context), "context_")
	return kv
}

// Measurement holds the data for user provided measurements
type Measurement struct {
	Values    map[string]float64 `json:"values,omitempty"`
	Timestamp time.Time          `json:"timestamp,omitempty"`
	Trace     TraceContext       `json:"trace,omitempty"`
	Type      string             `json:"type,omitempty"`
}

// KeyVal representation of the Measurement object
func (m Measurement) KeyVal() *KeyVal {
	kv := NewKeyVal()

	KeyValAdd(kv, "timestamp", m.Timestamp.String())
	KeyValAdd(kv, "kind", "measurement")

	keys := make([]string, 0, len(m.Values))
	for k := range m.Values {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, k := range keys {
		KeyValAdd(kv, k, fmt.Sprintf("%f", m.Values[k]))
	}
	MergeKeyVal(kv, m.Trace.KeyVal())
	return kv
}

// SDK holds metadata about the app agent that produced the event
type SDK struct {
	Name         string           `json:"name,omitempty"`
	Version      string           `json:"version,omitempty"`
	Integrations []SDKIntegration `json:"integrations,omitempty"`
}

// KeyVal produces key->value representation of Sdk metadata
func (sdk SDK) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "name", sdk.Name)
	KeyValAdd(kv, "version", sdk.Version)

	if len(sdk.Integrations) > 0 {
		integrations := make([]string, len(sdk.Integrations))

		for i, integration := range sdk.Integrations {
			integrations[i] = integration.String()
		}

		KeyValAdd(kv, "integrations", strings.Join(integrations, ","))
	}

	return kv
}

// SDKIntegration holds metadata about a plugin/integration on the app agent that collected and sent the event
type SDKIntegration struct {
	Name    string `json:"name,omitempty"`
	Version string `json:"version,omitempty"`
}

func (i SDKIntegration) String() string {
	return fmt.Sprintf("%s:%s", i.Name, i.Version)
}

// User holds metadata about the user related to an app event
type User struct {
	Email      string            `json:"email,omitempty"`
	ID         string            `json:"id,omitempty"`
	Username   string            `json:"username,omitempty"`
	Attributes map[string]string `json:"attributes,omitempty"`
}

// KeyVal produces a key->value representation User metadata
func (u User) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "email", u.Email)
	KeyValAdd(kv, "id", u.ID)
	KeyValAdd(kv, "username", u.Username)
	MergeKeyValWithPrefix(kv, KeyValFromMap(u.Attributes), "attr_")
	return kv
}

// Meta holds metadata about an app event
type Meta struct {
	SDK     SDK     `json:"sdk,omitempty"`
	App     App     `json:"app,omitempty"`
	User    User    `json:"user,omitempty"`
	Session Session `json:"session,omitempty"`
	Page    Page    `json:"page,omitempty"`
	Browser Browser `json:"browser,omitempty"`
}

// KeyVal produces key->value representation of the app event metadatga
func (m Meta) KeyVal() *KeyVal {
	kv := NewKeyVal()
	MergeKeyValWithPrefix(kv, m.SDK.KeyVal(), "sdk_")
	MergeKeyValWithPrefix(kv, m.App.KeyVal(), "app_")
	MergeKeyValWithPrefix(kv, m.User.KeyVal(), "user_")
	MergeKeyValWithPrefix(kv, m.Session.KeyVal(), "session_")
	MergeKeyValWithPrefix(kv, m.Page.KeyVal(), "page_")
	MergeKeyValWithPrefix(kv, m.Browser.KeyVal(), "browser_")
	return kv
}

// Session holds metadata about the browser session the event originates from
type Session struct {
	ID         string            `json:"id,omitempty"`
	Attributes map[string]string `json:"attributes,omitempty"`
}

// KeyVal produces key->value representation of the Session metadata
func (s Session) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "id", s.ID)
	MergeKeyValWithPrefix(kv, KeyValFromMap(s.Attributes), "attr_")
	return kv
}

// Page holds metadata about the web page event originates from
type Page struct {
	ID         string            `json:"id,omitempty"`
	URL        string            `json:"url,omitempty"`
	Attributes map[string]string `json:"attributes,omitempty"`
}

// KeyVal produces key->val representation of Page metadata
func (p Page) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "id", p.ID)
	KeyValAdd(kv, "url", p.URL)
	MergeKeyValWithPrefix(kv, KeyValFromMap(p.Attributes), "attr_")
	return kv
}

// App holds metadata about the application event originates from
type App struct {
	Name        string `json:"name,omitempty"`
	Release     string `json:"release,omitempty"`
	Version     string `json:"version,omitempty"`
	Environment string `json:"environment,omitempty"`
}

// KeyVal produces key-> value representation of App metadata
func (a App) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "name", a.Name)
	KeyValAdd(kv, "release", a.Release)
	KeyValAdd(kv, "version", a.Version)
	KeyValAdd(kv, "environment", a.Environment)
	return kv
}

// Browser holds metadata about a client's browser
type Browser struct {
	Name    string `json:"name,omitempty"`
	Version string `json:"version,omitempty"`
	OS      string `json:"os,omitempty"`
	Mobile  bool   `json:"mobile,omitempty"`
}

// KeyVal produces key->value representation of the Browser metadata
func (b Browser) KeyVal() *KeyVal {
	kv := NewKeyVal()
	KeyValAdd(kv, "name", b.Name)
	KeyValAdd(kv, "version", b.Version)
	KeyValAdd(kv, "os", b.OS)
	KeyValAdd(kv, "mobile", fmt.Sprintf("%v", b.Mobile))
	return kv
}