// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package caddyhttp

import (
	"net/http"
	"strconv"
	"strings"

	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
)

// ResponseMatcher is a type which can determine if an
// HTTP response matches some criteria.
type ResponseMatcher struct {
	// If set, one of these status codes would be required.
	// A one-digit status can be used to represent all codes
	// in that class (e.g. 3 for all 3xx codes).
	StatusCode []int `json:"status_code,omitempty"`

	// If set, each header specified must be one of the
	// specified values, with the same logic used by the
	// [request header matcher](/docs/json/apps/http/servers/routes/match/header/).
	Headers http.Header `json:"headers,omitempty"`
}

// Match returns true if the given statusCode and hdr match rm.
func (rm ResponseMatcher) Match(statusCode int, hdr http.Header) bool {
	if !rm.matchStatusCode(statusCode) {
		return false
	}
	return matchHeaders(hdr, rm.Headers, "", []string{}, nil)
}

func (rm ResponseMatcher) matchStatusCode(statusCode int) bool {
	if rm.StatusCode == nil {
		return true
	}
	for _, code := range rm.StatusCode {
		if StatusCodeMatches(statusCode, code) {
			return true
		}
	}
	return false
}

// ParseNamedResponseMatcher parses the tokens of a named response matcher.
//
//	@name {
//	    header <field> [<value>]
//	    status <code...>
//	}
//
// Or, single line syntax:
//
//	@name [header <field> [<value>]] | [status <code...>]
func ParseNamedResponseMatcher(d *caddyfile.Dispenser, matchers map[string]ResponseMatcher) error {
	d.Next() // consume matcher name
	definitionName := d.Val()

	if _, ok := matchers[definitionName]; ok {
		return d.Errf("matcher is defined more than once: %s", definitionName)
	}

	matcher := ResponseMatcher{}
	for nesting := d.Nesting(); d.NextArg() || d.NextBlock(nesting); {
		switch d.Val() {
		case "header":
			if matcher.Headers == nil {
				matcher.Headers = http.Header{}
			}

			// reuse the header request matcher's unmarshaler
			headerMatcher := MatchHeader(matcher.Headers)
			err := headerMatcher.UnmarshalCaddyfile(d.NewFromNextSegment())
			if err != nil {
				return err
			}

			matcher.Headers = http.Header(headerMatcher)
		case "status":
			if matcher.StatusCode == nil {
				matcher.StatusCode = []int{}
			}

			args := d.RemainingArgs()
			if len(args) == 0 {
				return d.ArgErr()
			}

			for _, arg := range args {
				if len(arg) == 3 && strings.HasSuffix(arg, "xx") {
					arg = arg[:1]
				}
				statusNum, err := strconv.Atoi(arg)
				if err != nil {
					return d.Errf("bad status value '%s': %v", arg, err)
				}
				matcher.StatusCode = append(matcher.StatusCode, statusNum)
			}
		default:
			return d.Errf("unrecognized response matcher %s", d.Val())
		}
	}
	matchers[definitionName] = matcher
	return nil
}