package installer

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"path/filepath"
	"strconv"
	"strings"
	"text/template"

	"github.com/giolekva/pcloud/core/installer/soft"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/util/intstr"
	"sigs.k8s.io/yaml"
)

type ClusterNetworkConfigurator interface {
	AddCluster(name string, ingressIP net.IP) error
	RemoveCluster(name string, ingressIP net.IP) error
	AddProxy(src int, dst string, protocol Protocol) (string, error)
	AddIngressProxy(src, dst string) error
	RemoveProxy(src int, dst string, protocol Protocol) error
	RemoveIngressProxy(src, dst string) error
}

type NginxProxyConfigurator struct {
	PrivateSubdomain string
	DNSAPIAddr       string
	Repo             soft.RepoIO
	ConfigPath       string
	ServicePath      string
}

type createARecordReq struct {
	Entry string `json:"entry"`
	IP    net.IP `json:"text"`
}

func (c *NginxProxyConfigurator) AddCluster(name string, ingressIP net.IP) error {
	req := createARecordReq{
		Entry: fmt.Sprintf("*.%s.cluster.%s", name, c.PrivateSubdomain),
		IP:    ingressIP,
	}
	var buf bytes.Buffer
	if err := json.NewEncoder(&buf).Encode(req); err != nil {
		return err
	}
	resp, err := http.Post(fmt.Sprintf("%s/create-a-record", c.DNSAPIAddr), "application/json", &buf)
	if err != nil {
		return err
	}
	if resp.StatusCode != http.StatusOK {
		var buf bytes.Buffer
		io.Copy(&buf, resp.Body)
		return errors.New(buf.String())
	}
	return nil
}

func (c *NginxProxyConfigurator) RemoveCluster(name string, ingressIP net.IP) error {
	req := createARecordReq{
		Entry: fmt.Sprintf("*.%s.cluster.%s", name, c.PrivateSubdomain),
		IP:    ingressIP,
	}
	var buf bytes.Buffer
	if err := json.NewEncoder(&buf).Encode(req); err != nil {
		return err
	}
	resp, err := http.Post(fmt.Sprintf("%s/delete-a-record", c.DNSAPIAddr), "application/json", &buf)
	if err != nil {
		return err
	}
	if resp.StatusCode != http.StatusOK {
		var buf bytes.Buffer
		io.Copy(&buf, resp.Body)
		return errors.New(buf.String())
	}
	return nil
}

func (c *NginxProxyConfigurator) AddProxy(src int, dst string, protocol Protocol) (string, error) {
	var namespace string
	_, err := c.Repo.Do(func(fs soft.RepoFS) (string, error) {
		if err := func() error {
			r, err := fs.Reader(c.ServicePath)
			if err != nil {
				return err
			}
			defer r.Close()
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, r); err != nil {
				return err
			}
			var svc corev1.Service
			if err := yaml.Unmarshal(buf.Bytes(), &svc); err != nil {
				return err
			}
			svc.Spec.Ports = append(svc.Spec.Ports, corev1.ServicePort{
				Name:       fmt.Sprintf("p%d", src),
				Protocol:   corev1.Protocol(ProtocolToString(protocol)),
				Port:       int32(src),
				TargetPort: intstr.FromInt(src),
			})
			w, err := fs.Writer(c.ServicePath)
			if err != nil {
				return err
			}
			defer w.Close()
			tmp, err := yaml.Marshal(svc)
			if err != nil {
				return err
			}
			if _, err := io.Copy(w, bytes.NewReader(tmp)); err != nil {
				return err
			}
			return nil
		}(); err != nil {
			return "", err
		}
		cfg, err := func() (NginxProxyConfig, error) {
			r, err := fs.Reader(c.ConfigPath)
			if err != nil {
				return NginxProxyConfig{}, err
			}
			defer r.Close()
			return ParseNginxProxyConfig(r)
		}()
		if err != nil {
			return "", err
		}
		namespace = cfg.Namespace
		var proxyMap map[int]string
		switch protocol {
		case ProtocolTCP:
			proxyMap = cfg.TCP
		case ProtocolUDP:
			proxyMap = cfg.UDP
		default:
			return "", fmt.Errorf("invalid protocol: %v", protocol)
		}
		// TODO(gio): check for already existing mapping
		proxyMap[src] = dst
		w, err := fs.Writer(c.ConfigPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if err := cfg.Render(w); err != nil {
			return "", err
		}
		nginxPath := filepath.Join(filepath.Dir(c.ConfigPath), "ingress-nginx.yaml")
		nginx, err := func() (map[string]any, error) {
			r, err := fs.Reader(nginxPath)
			if err != nil {
				return nil, err
			}
			defer r.Close()
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, r); err != nil {
				return nil, err
			}
			ret := map[string]any{}
			if err := yaml.Unmarshal(buf.Bytes(), &ret); err != nil {
				return nil, err
			}
			return ret, nil
		}()
		if err != nil {
			return "", err
		}
		buf, err := yaml.Marshal(nginx)
		if err != nil {
			return "", err
		}
		w, err = fs.Writer(nginxPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if _, err := io.Copy(w, bytes.NewReader(buf)); err != nil {
			return "", err
		}
		return fmt.Sprintf("add proxy mapping: %d %s", src, dst), nil
	})
	if err != nil {
		return "", err
	}
	return namespace, nil
}

func (c *NginxProxyConfigurator) AddIngressProxy(src, dst string) error {
	_, err := c.Repo.Do(func(fs soft.RepoFS) (string, error) {
		cfg, err := func() (NginxProxyConfig, error) {
			r, err := fs.Reader(c.ConfigPath)
			if err != nil {
				return NginxProxyConfig{}, err
			}
			defer r.Close()
			return ParseNginxProxyConfig(r)
		}()
		if err != nil {
			return "", err
		}
		if v, ok := cfg.Ingress[src]; ok && v != dst {
			return "", fmt.Errorf("wrong mapping %s already exists (%s)", src, v)
		}
		cfg.Ingress[src] = dst
		w, err := fs.Writer(c.ConfigPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if err := cfg.Render(w); err != nil {
			return "", err
		}
		nginxPath := filepath.Join(filepath.Dir(c.ConfigPath), "ingress-nginx.yaml")
		nginx, err := func() (map[string]any, error) {
			r, err := fs.Reader(nginxPath)
			if err != nil {
				return nil, err
			}
			defer r.Close()
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, r); err != nil {
				return nil, err
			}
			ret := map[string]any{}
			if err := yaml.Unmarshal(buf.Bytes(), &ret); err != nil {
				return nil, err
			}
			return ret, nil
		}()
		if err != nil {
			return "", err
		}
		buf, err := yaml.Marshal(nginx)
		if err != nil {
			return "", err
		}
		w, err = fs.Writer(nginxPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if _, err := io.Copy(w, bytes.NewReader(buf)); err != nil {
			return "", err
		}
		return fmt.Sprintf("add ingress proxy mapping: %s %s", src, dst), nil
	})
	return err
}

func (c *NginxProxyConfigurator) RemoveProxy(src int, dst string, protocol Protocol) error {
	_, err := c.Repo.Do(func(fs soft.RepoFS) (string, error) {
		if err := func() error {
			r, err := fs.Reader(c.ServicePath)
			if err != nil {
				return err
			}
			defer r.Close()
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, r); err != nil {
				return err
			}
			var svc corev1.Service
			if err := yaml.Unmarshal(buf.Bytes(), &svc); err != nil {
				return err
			}
			for i, p := range svc.Spec.Ports {
				if p.Port == int32(src) {
					svc.Spec.Ports = append(svc.Spec.Ports[:i], svc.Spec.Ports[i+1:]...)
					break
				}
			}
			w, err := fs.Writer(c.ServicePath)
			if err != nil {
				return err
			}
			defer w.Close()
			tmp, err := yaml.Marshal(svc)
			if err != nil {
				return err
			}
			if _, err := io.Copy(w, bytes.NewReader(tmp)); err != nil {
				return err
			}
			return nil
		}(); err != nil {
			return "", err
		}
		cfg, err := func() (NginxProxyConfig, error) {
			r, err := fs.Reader(c.ConfigPath)
			if err != nil {
				return NginxProxyConfig{}, err
			}
			defer r.Close()
			return ParseNginxProxyConfig(r)
		}()
		if err != nil {
			return "", err
		}
		var proxyMap map[int]string
		switch protocol {
		case ProtocolTCP:
			proxyMap = cfg.TCP
		case ProtocolUDP:
			proxyMap = cfg.UDP
		default:
			return "", fmt.Errorf("invalid protocol: %v", protocol)
		}
		// TODO(gio): check for already existing mapping
		delete(proxyMap, src)
		w, err := fs.Writer(c.ConfigPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if err := cfg.Render(w); err != nil {
			return "", err
		}
		nginxPath := filepath.Join(filepath.Dir(c.ConfigPath), "ingress-nginx.yaml")
		nginx, err := func() (map[string]any, error) {
			r, err := fs.Reader(nginxPath)
			if err != nil {
				return nil, err
			}
			defer r.Close()
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, r); err != nil {
				return nil, err
			}
			ret := map[string]any{}
			if err := yaml.Unmarshal(buf.Bytes(), &ret); err != nil {
				return nil, err
			}
			return ret, nil
		}()
		if err != nil {
			return "", err
		}
		buf, err := yaml.Marshal(nginx)
		if err != nil {
			return "", err
		}
		w, err = fs.Writer(nginxPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if _, err := io.Copy(w, bytes.NewReader(buf)); err != nil {
			return "", err
		}
		return fmt.Sprintf("remove proxy mapping: %d %s", src, dst), nil
	})
	return err
}

func (c *NginxProxyConfigurator) RemoveIngressProxy(src, dst string) error {
	_, err := c.Repo.Do(func(fs soft.RepoFS) (string, error) {
		cfg, err := func() (NginxProxyConfig, error) {
			r, err := fs.Reader(c.ConfigPath)
			if err != nil {
				return NginxProxyConfig{}, err
			}
			defer r.Close()
			return ParseNginxProxyConfig(r)
		}()
		if err != nil {
			return "", err
		}
		if v, ok := cfg.Ingress[src]; !ok || v != dst {
			return "", fmt.Errorf("wrong mapping from source: %s actual: %s expected: %s", src, v, dst)
		}
		delete(cfg.Ingress, src)
		w, err := fs.Writer(c.ConfigPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if err := cfg.Render(w); err != nil {
			return "", err
		}
		nginxPath := filepath.Join(filepath.Dir(c.ConfigPath), "ingress-nginx.yaml")
		nginx, err := func() (map[string]any, error) {
			r, err := fs.Reader(nginxPath)
			if err != nil {
				return nil, err
			}
			defer r.Close()
			var buf bytes.Buffer
			if _, err := io.Copy(&buf, r); err != nil {
				return nil, err
			}
			ret := map[string]any{}
			if err := yaml.Unmarshal(buf.Bytes(), &ret); err != nil {
				return nil, err
			}
			return ret, nil
		}()
		if err != nil {
			return "", err
		}
		buf, err := yaml.Marshal(nginx)
		if err != nil {
			return "", err
		}
		w, err = fs.Writer(nginxPath)
		if err != nil {
			return "", err
		}
		defer w.Close()
		if _, err := io.Copy(w, bytes.NewReader(buf)); err != nil {
			return "", err
		}
		return fmt.Sprintf("remove proxy mapping: %s %s", src, dst), nil
	})
	return err
}

type Protocol int

const (
	ProtocolTCP Protocol = iota
	ProtocolUDP
)

func ProtocolToString(p Protocol) string {
	if p == ProtocolTCP {
		return "TCP"
	} else {
		return "UDP"
	}
}

type NginxProxyConfig struct {
	Namespace   string
	PID         string
	IngressPort int
	Resolvers   []net.IP
	Ingress     map[string]string
	TCP         map[int]string
	UDP         map[int]string
	PreConf     []string
}

func parseProtocol(s string) (Protocol, error) {
	switch strings.ToLower(s) {
	case "tcp":
		return ProtocolTCP, nil
	case "udp":
		return ProtocolUDP, nil
	default:
		return ProtocolUDP, fmt.Errorf("invalid protocol: %s", s)
	}
}

func ParseNginxProxyConfig(r io.Reader) (NginxProxyConfig, error) {
	var buf strings.Builder
	if _, err := io.Copy(&buf, r); err != nil {
		return NginxProxyConfig{}, err
	}
	ret := NginxProxyConfig{
		IngressPort: -1,
		Resolvers:   nil,
		Ingress:     make(map[string]string),
		TCP:         make(map[int]string),
		UDP:         make(map[int]string),
	}
	lines := strings.Split(buf.String(), "\n")
	insidePreConf := true
	insideHttp := false
	insideMap := false
	insideStream := false
	streamPort := -1
	streamPortProtocol := ProtocolTCP
	for _, l := range lines {
		items := strings.Fields(strings.TrimSuffix(l, ";"))
		if len(items) == 0 {
			continue
		}
		if strings.Contains(l, "nginx.conf") {
			ret.PreConf = append(ret.PreConf, l)
			insidePreConf = false
		} else if insidePreConf {
			ret.PreConf = append(ret.PreConf, l)
			items := strings.Fields(l)
			if items[0] == "namespace:" {
				ret.Namespace = items[1]
			}
		} else if items[0] == "pid" {

			ret.PID = items[1]
		} else if items[0] == "http" {
			insideHttp = true
		} else if insideHttp && items[0] == "map" {
			insideMap = true
		} else if items[0] == "stream" {
			insideHttp = false
			insideMap = false
			insideStream = true
		} else if strings.Contains(l, "listen") {
			if len(items) < 2 {
				return NginxProxyConfig{}, fmt.Errorf("invalid listen: %s", l)
			}
			port, err := strconv.Atoi(items[1])
			if err != nil {
				return NginxProxyConfig{}, err
			}
			if insideHttp {
				if len(items) > 2 {
					return NginxProxyConfig{}, fmt.Errorf("invalid http listen: %s", l)
				}
				ret.IngressPort = port
			} else {
				if !insideStream {
					return NginxProxyConfig{}, fmt.Errorf("invalid state, expected to be inside stream section")
				}
				streamPort = port
				if len(items) == 3 {
					streamPortProtocol, err = parseProtocol(items[2])
					if err != nil {
						return NginxProxyConfig{}, err
					}
				} else {
					streamPortProtocol = ProtocolTCP
				}
			}
		} else if insideHttp && strings.Contains(l, "resolver") {
			if len(items) < 2 {
				return NginxProxyConfig{}, fmt.Errorf("invalid resolver: %s", l)
			}
			ip := net.ParseIP(items[1])
			if ip == nil {
				return NginxProxyConfig{}, fmt.Errorf("invalid resolver ip: %s", l)
			}
			ret.Resolvers = append(ret.Resolvers, ip)
		} else if insideHttp && insideMap {
			if items[0] == "}" {
				insideMap = false
				continue
			}
			if len(items) < 2 {
				return NginxProxyConfig{}, fmt.Errorf("invalid map: %s", l)
			}
			ret.Ingress[items[0]] = items[1]
		} else if insideStream && strings.Contains(l, "proxy_pass") {
			if streamPort == -1 {
				return NginxProxyConfig{}, fmt.Errorf("invalid state, expected server port to be defined")
			}
			if len(items) < 2 {
				return NginxProxyConfig{}, fmt.Errorf("invalid proxy_pass: %s", l)
			}
			if streamPortProtocol == ProtocolTCP {
				ret.TCP[streamPort] = items[1]
			} else {
				ret.UDP[streamPort] = items[1]
			}
		}
	}
	return ret, nil
}

func (c NginxProxyConfig) Render(w io.Writer) error {
	for _, l := range c.PreConf {
		fmt.Fprintln(w, l)
	}
	tmpl, err := template.New("nginx.conf").Parse(nginxConfigTmpl)
	if err != nil {
		return err
	}
	return tmpl.Execute(w, c)
}

const nginxConfigTmpl = `    worker_processes  1;
    worker_rlimit_nofile 8192;
    {{- if .PID }}
    pid {{ .PID }};
    {{- end }}
    events {
        worker_connections  1024;
    }
    http {
        map $http_host $backend {
            {{- range $from, $to := .Ingress }}
            {{ $from }} {{ $to }};
            {{- end }}
        }
        server {
            listen {{ .IngressPort }};
            location / {
                {{- range .Resolvers }}
                resolver {{ . }};
                {{- end }}
                proxy_pass http://$backend;
            }
        }
    }
    {{- if or .TCP .UDP }}
    stream {
        {{- range $port, $upstream := .TCP }}
        server {
            listen {{ $port }};
            resolver 100.100.100.100;
            proxy_pass {{ $upstream }};
        }
        {{- end  }}
        {{- range $port, $upstream := .UDP }}
        server {
            listen {{ $port }} udp;
            proxy_pass {{ $upstream }};
        }
        {{- end  }}
    }
    {{- end }}`