package middleware

import (
	"context"
	"time"

	apierrors "git.yuntuo.hk/k2safe/go-omni/errors"
	"git.yuntuo.hk/k2safe/go-omni/httpx"
)

// Timeout applies a cooperative deadline to handlers and downstream calls.
// It does not spawn a goroutine or race a handler's response. Business code must
// observe Context().Done(); an already committed response cannot be replaced.
func Timeout(duration time.Duration) httpx.Middleware {
	if duration <= 0 {
		panic("middleware: timeout must be positive")
	}
	return func(next httpx.Handler) httpx.Handler {
		return func(c *httpx.Context) error {
			parent := c.Context()
			ctx, cancel := context.WithTimeout(parent, duration)
			defer cancel()
			c.WithContext(ctx)
			defer c.WithContext(parent)
			if ctx.Err() != nil {
				return apierrors.New(504, "REQUEST_TIMEOUT", "request deadline exceeded")
			}
			err := next(c)
			if ctx.Err() == context.DeadlineExceeded && !c.Responded() {
				return apierrors.New(504, "REQUEST_TIMEOUT", "request deadline exceeded").WithCause(err)
			}
			return err
		}
	}
}