context.go

package gin_grpc

import (
	"context"
	"math"
	"sync"
	"time"
)

type Context struct {
	ctx context.Context

	handlers HandlersChain
	index    int8

	engine *Engine

	Req  *Request
	Resp *Response

	// This mutex protects Keys map.
	mu sync.RWMutex

	// Keys is a key/value pair exclusively for the context of each request.
	Keys map[string]any

	// Errors is a list of errors attached to all the handlers/middlewares who used this context.
	Errors Errors
}

// abortIndex represents a typical value used in abort functions.
const abortIndex int8 = math.MaxInt8 >> 1

func (c *Context) reset() {
	c.handlers = nil
	c.index = -1

	c.Req.req = nil
	c.Resp.resp = nil

	c.Keys = nil
	c.Errors.Clear()
}

// Copy returns a copy of the current context that can be safely used outside the request's scope.
// This has to be used when the context has to be passed to a goroutine.
func (c *Context) Copy() *Context {
	cp := Context{
		Req:    c.Req,
		Resp:   c.Resp,
		engine: c.engine,
	}
	cp.index = abortIndex
	cp.handlers = nil
	cp.Keys = map[string]any{}
	for k, v := range c.Keys {
		cp.Keys[k] = v
	}
	return &cp
}

// Next should be used only inside middleware.
// It executes the pending handlers in the chain inside the calling handler.
// See example in GitHub.
func (c *Context) Next() {
	c.index++
	for c.index < int8(len(c.handlers)) {
		c.handlers[c.index](c)
		c.index++
	}
}

// IsAborted returns true if the current context was aborted.
func (c *Context) IsAborted() bool {
	return c.index >= abortIndex
}

// Abort prevents pending handlers from being called. Note that this will not stop the current handler.
// Let's say you have an authorization middleware that validates that the current request is authorized.
// If the authorization fails (ex: the password does not match), call Abort to ensure the remaining handlers
// for this request are not called.
func (c *Context) Abort() {
	c.index = abortIndex
}

// AbortWithError calls `Abort()` and `Error()` internally.
// This method stops the chain, writes the status code and pushes the specified error to `c.Errors`.
// See Context.Error() for more details.
func (c *Context) AbortWithError(err error) {
	c.Abort()
	c.Error(err)
}

// Error attaches an error to the current context. The error is pushed to a list of errors.
// It's a good idea to call Error for each error that occurred during the resolution of a request.
// A middleware can be used to collect all the errors and push them to a database together,
// print a log, or append it in the rpc response.
// Error will panic if err is nil.
func (c *Context) Error(err error) {
	if err == nil {
		panic("err is nil")
	}

	c.Errors.Append(err)
}

// BindRequest calls Request.Bind(req)
func (c *Context) BindRequest(req any) {
	c.Req.Bind(req)
}

// GetRequestField calls Request.GetField(field)
func (c *Context) GetRequestField(field string) (value any) {
	return c.Req.GetField(field)
}

// Response calls Response.Set(resp)
func (c *Context) Response(resp any) {
	c.Resp.Set(resp)
}

// ResponseField calls Response.SetField(field, value)
func (c *Context) ResponseField(field string, value any) {
	c.Resp.SetField(field, value)
}

// ResponseFields calls Response.SetFields(fields)
func (c *Context) ResponseFields(fields H) {
	c.Resp.SetFields(fields)
}

// Set is used to store a new key/value pair exclusively for this context.
// It also lazy initializes  c.Keys if it was not used previously.
func (c *Context) Set(key string, value any) {
	c.mu.Lock()
	defer c.mu.Unlock()
	if c.Keys == nil {
		c.Keys = make(map[string]any)
	}

	c.Keys[key] = value
}

// Get returns the value for the given key, ie: (value, true).
// If the value does not exist it returns (nil, false)
func (c *Context) Get(key string) (value any, exists bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()
	value, exists = c.Keys[key]
	return
}

// GetString returns the value associated with the key as a string.
func (c *Context) GetString(key string) (s string) {
	if val, ok := c.Get(key); ok && val != nil {
		s, _ = val.(string)
	}
	return
}

// GetBool returns the value associated with the key as a boolean.
func (c *Context) GetBool(key string) (b bool) {
	if val, ok := c.Get(key); ok && val != nil {
		b, _ = val.(bool)
	}
	return
}

// GetInt returns the value associated with the key as an integer.
func (c *Context) GetInt(key string) (i int) {
	if val, ok := c.Get(key); ok && val != nil {
		i, _ = val.(int)
	}
	return
}

// GetInt64 returns the value associated with the key as an integer.
func (c *Context) GetInt64(key string) (i64 int64) {
	if val, ok := c.Get(key); ok && val != nil {
		i64, _ = val.(int64)
	}
	return
}

// GetUint returns the value associated with the key as an unsigned integer.
func (c *Context) GetUint(key string) (ui uint) {
	if val, ok := c.Get(key); ok && val != nil {
		ui, _ = val.(uint)
	}
	return
}

// GetUint64 returns the value associated with the key as an unsigned integer.
func (c *Context) GetUint64(key string) (ui64 uint64) {
	if val, ok := c.Get(key); ok && val != nil {
		ui64, _ = val.(uint64)
	}
	return
}

// GetFloat64 returns the value associated with the key as a float64.
func (c *Context) GetFloat64(key string) (f64 float64) {
	if val, ok := c.Get(key); ok && val != nil {
		f64, _ = val.(float64)
	}
	return
}

// GetTime returns the value associated with the key as time.
func (c *Context) GetTime(key string) (t time.Time) {
	if val, ok := c.Get(key); ok && val != nil {
		t, _ = val.(time.Time)
	}
	return
}

// GetDuration returns the value associated with the key as a duration.
func (c *Context) GetDuration(key string) (d time.Duration) {
	if val, ok := c.Get(key); ok && val != nil {
		d, _ = val.(time.Duration)
	}
	return
}

// GetStringSlice returns the value associated with the key as a slice of strings.
func (c *Context) GetStringSlice(key string) (ss []string) {
	if val, ok := c.Get(key); ok && val != nil {
		ss, _ = val.([]string)
	}
	return
}

// GetStringMap returns the value associated with the key as a map of interfaces.
func (c *Context) GetStringMap(key string) (sm map[string]any) {
	if val, ok := c.Get(key); ok && val != nil {
		sm, _ = val.(map[string]any)
	}
	return
}

// GetStringMapString returns the value associated with the key as a map of strings.
func (c *Context) GetStringMapString(key string) (sms map[string]string) {
	if val, ok := c.Get(key); ok && val != nil {
		sms, _ = val.(map[string]string)
	}
	return
}

// GetStringMapStringSlice returns the value associated with the key as a map to a slice of strings.
func (c *Context) GetStringMapStringSlice(key string) (smss map[string][]string) {
	if val, ok := c.Get(key); ok && val != nil {
		smss, _ = val.(map[string][]string)
	}
	return
}