package timeout

import (
	"context"
	"errors"

	"github.com/gofiber/fiber/v3"
)

// New enforces a timeout for each incoming request. If the timeout expires or
// any of the specified errors occur, fiber.ErrRequestTimeout is returned.
func New(h fiber.Handler, config ...Config) fiber.Handler {
	cfg := configDefault(config...)

	return func(ctx fiber.Ctx) error {
		if cfg.Next != nil && cfg.Next(ctx) {
			return h(ctx)
		}

		timeout := cfg.Timeout
		if timeout <= 0 {
			return runHandler(ctx, h, cfg)
		}

		tCtx, cancel := context.WithTimeout(ctx, timeout)
		defer cancel()

		err := runHandler(ctx, h, cfg)

		if errors.Is(tCtx.Err(), context.DeadlineExceeded) {
			if cfg.OnTimeout != nil {
				return cfg.OnTimeout(ctx)
			}
			return fiber.ErrRequestTimeout
		}
		return err
	}
}

// runHandler executes the handler and returns fiber.ErrRequestTimeout if it
// sees a deadline exceeded error or one of the custom "timeout-like" errors.
func runHandler(c fiber.Ctx, h fiber.Handler, cfg Config) error {
	err := h(c)
	if err != nil && (errors.Is(err, context.DeadlineExceeded) || (len(cfg.Errors) > 0 && isCustomError(err, cfg.Errors))) {
		if cfg.OnTimeout != nil {
			return cfg.OnTimeout(c)
		}
		return fiber.ErrRequestTimeout
	}
	return err
}

// isCustomError checks whether err matches any error in errList using errors.Is.
func isCustomError(err error, errList []error) bool {
	for _, e := range errList {
		if errors.Is(err, e) {
			return true
		}
	}
	return false
}