package web

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"

	"git.veillax.com/Veillax/megalodon/internal/ark"
	"git.veillax.com/Veillax/megalodon/internal/config"
	"git.veillax.com/Veillax/megalodon/internal/manager"
)

func (s *Server) me(w http.ResponseWriter, r *http.Request, p principal) {
	type macro struct {
		Name string `json:"name"`
	}
	var macros []macro
	for _, m := range s.cfg.Get().Macros {
		if p.Role.Allows(m.Role) {
			macros = append(macros, macro{m.Name})
		}
	}
	writeJSON(w, map[string]any{"name": p.Name, "role": p.Role, "version": s.version, "macros": macros, "reference": ark.Reference})
}

// ---- servers ----

func (s *Server) listServers(w http.ResponseWriter, r *http.Request, p principal) {
	writeJSON(w, s.m.Views())
}

var nonID = regexp.MustCompile(`[^a-z0-9]+`)

func (s *Server) addServer(w http.ResponseWriter, r *http.Request, p principal) {
	var in config.Server
	if !decode(w, r, &in) {
		return
	}
	if in.ID == "" {
		in.ID = strings.Trim(nonID.ReplaceAllString(strings.ToLower(in.Name), "-"), "-")
	}
	err := s.cfg.Update(func(c *config.Config) error {
		c.Servers = append(c.Servers, in)
		return nil
	})
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.m.Reload()
	s.m.Audit(p.Name, in.ID, "added server "+in.Name)
	writeJSON(w, map[string]string{"id": in.ID})
}

func (s *Server) editServer(w http.ResponseWriter, r *http.Request, p principal) {
	id := r.PathValue("id")
	var in config.Server
	if !decode(w, r, &in) {
		return
	}
	in.ID = id
	found := false
	err := s.cfg.Update(func(c *config.Config) error {
		for k := range c.Servers {
			if c.Servers[k].ID == id {
				if in.Password == "" { // blank means keep the current one
					in.Password = c.Servers[k].Password
				}
				c.Servers[k], found = in, true
			}
		}
		return nil
	})
	switch {
	case err != nil:
		fail(w, http.StatusBadRequest, err.Error())
	case !found:
		fail(w, http.StatusNotFound, "no such server")
	default:
		s.m.Reload()
		s.m.Audit(p.Name, id, "edited server settings")
		writeJSON(w, map[string]bool{"ok": true})
	}
}

func (s *Server) deleteServer(w http.ResponseWriter, r *http.Request, p principal) {
	id := r.PathValue("id")
	err := s.cfg.Update(func(c *config.Config) error {
		var keep []config.Server
		for _, sv := range c.Servers {
			if sv.ID != id {
				keep = append(keep, sv)
			}
		}
		c.Servers = keep
		for k := range c.Jobs { // a job aimed only at this server would now hit every server
			var left []string
			for _, sid := range c.Jobs[k].Servers {
				if sid != id {
					left = append(left, sid)
				}
			}
			if len(c.Jobs[k].Servers) > 0 && len(left) == 0 {
				c.Jobs[k].Enabled = false
			}
			c.Jobs[k].Servers = left
		}
		return nil
	})
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.m.Reload()
	s.m.Audit(p.Name, "", "removed server "+id)
	writeJSON(w, map[string]bool{"ok": true})
}

func (s *Server) samples(w http.ResponseWriter, r *http.Request, p principal) {
	i, ok := s.m.Instance(r.PathValue("id"))
	if !ok {
		fail(w, http.StatusNotFound, "no such server")
		return
	}
	writeJSON(w, i.Samples())
}

// ---- actions ----

func (s *Server) serverAction(w http.ResponseWriter, r *http.Request, p principal) {
	var a manager.Action
	if !decode(w, r, &a) {
		return
	}
	a.Servers = []string{r.PathValue("id")}
	s.runAction(w, p, a)
}

func (s *Server) clusterAction(w http.ResponseWriter, r *http.Request, p principal) {
	var a manager.Action
	if !decode(w, r, &a) {
		return
	}
	s.runAction(w, p, a)
}

func (s *Server) runAction(w http.ResponseWriter, p principal, a manager.Action) {
	if !p.Role.Allows(manager.ActionRole(a.Name)) {
		fail(w, http.StatusForbidden, "your role cannot do this")
		return
	}
	if a.Minutes < 0 || a.Minutes > 24*60*365 {
		fail(w, http.StatusBadRequest, "minutes out of range")
		return
	}
	results, err := s.m.Do(p.Name, a)
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	writeJSON(w, results)
}

func (s *Server) runMacro(w http.ResponseWriter, r *http.Request, p principal) {
	var in struct{ Name string }
	if !decode(w, r, &in) {
		return
	}
	for _, m := range s.cfg.Get().Macros {
		if m.Name == in.Name {
			if !p.Role.Allows(m.Role) {
				fail(w, http.StatusForbidden, "your role cannot run this macro")
				return
			}
			res, err := s.m.RunMacro(p.Name, r.PathValue("id"), m)
			if err != nil {
				fail(w, http.StatusBadRequest, err.Error())
				return
			}
			writeJSON(w, res)
			return
		}
	}
	fail(w, http.StatusNotFound, "no such macro")
}

func (s *Server) runJob(w http.ResponseWriter, r *http.Request, p principal) {
	for _, j := range s.cfg.Get().Jobs {
		if j.ID == r.PathValue("id") {
			writeJSON(w, s.m.RunJob(j, p.Name+" (run now)"))
			return
		}
	}
	fail(w, http.StatusNotFound, "no such job")
}

func (s *Server) testNotify(w http.ResponseWriter, r *http.Request, p principal) {
	var in struct{ Name string }
	if !decode(w, r, &in) {
		return
	}
	if err := s.m.TestNotify(in.Name); err != nil {
		fail(w, http.StatusBadGateway, err.Error())
		return
	}
	writeJSON(w, map[string]bool{"ok": true})
}

// ---- events, players, bans ----

func (s *Server) events(w http.ResponseWriter, r *http.Request, p principal) {
	q := r.URL.Query()
	f := manager.Filter{Server: q.Get("server"), Query: q.Get("q")}
	if t := q.Get("type"); t != "" {
		f.Types = strings.Split(t, ",")
	}
	f.Before, _ = strconv.ParseInt(q.Get("before"), 10, 64)
	f.Limit, _ = strconv.Atoi(q.Get("limit"))
	// Console audit lines can hold commands with sensitive values; only moderators and up see them.
	events := s.m.Hub().Recent(f)
	if !p.Role.Allows(config.Moderator) {
		kept := events[:0]
		for _, e := range events {
			if e.Type != "audit" && e.Type != "error" {
				kept = append(kept, e)
			}
		}
		events = kept
	}
	writeJSON(w, events)
}

func (s *Server) stream(w http.ResponseWriter, r *http.Request, p principal) {
	fl, ok := w.(http.Flusher)
	if !ok {
		fail(w, http.StatusInternalServerError, "streaming not supported")
		return
	}
	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("X-Accel-Buffering", "no")
	ch, cancel := s.m.Hub().Subscribe()
	defer cancel()
	fmt.Fprint(w, ": connected\n\n")
	fl.Flush()
	ping := time.NewTicker(20 * time.Second)
	defer ping.Stop()
	for {
		select {
		case <-r.Context().Done():
			return
		case <-ping.C:
			fmt.Fprint(w, ": ping\n\n")
			fl.Flush()
		case e := <-ch:
			if !p.Role.Allows(config.Moderator) && (e.Type == "audit" || e.Type == "error") {
				continue
			}
			b, _ := jsonBytes(e)
			fmt.Fprintf(w, "data: %s\n\n", b)
			fl.Flush()
		}
	}
}

func (s *Server) players(w http.ResponseWriter, r *http.Request, p principal) {
	recs := s.m.Players()
	if !p.Role.Allows(config.Moderator) {
		for k := range recs {
			recs[k].Notes = "" // moderator notes stay between moderators
		}
	}
	writeJSON(w, recs)
}

func (s *Server) annotate(w http.ResponseWriter, r *http.Request, p principal) {
	var in struct {
		Notes string `json:"notes"`
		Watch bool   `json:"watch"`
	}
	if !decode(w, r, &in) {
		return
	}
	if err := s.m.Annotate(r.PathValue("id"), in.Notes, in.Watch); err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	writeJSON(w, map[string]bool{"ok": true})
}

func (s *Server) bans(w http.ResponseWriter, r *http.Request, p principal) {
	writeJSON(w, s.m.Bans())
}

// ---- settings ----

type settings struct {
	Jobs       []config.Job      `json:"jobs"`
	Macros     []config.Macro    `json:"macros"`
	Notify     []config.Notify   `json:"notify"`
	Welcome    config.Welcome    `json:"welcome"`
	ChatFilter config.ChatFilter `json:"chat_filter"`
}

func (s *Server) getSettings(w http.ResponseWriter, r *http.Request, p principal) {
	c := s.cfg.Get()
	writeJSON(w, settings{c.Jobs, c.Macros, c.Notify, c.Welcome, c.ChatFilter})
}

func (s *Server) putSettings(w http.ResponseWriter, r *http.Request, p principal) {
	var in settings
	if !decode(w, r, &in) {
		return
	}
	for k := range in.Jobs {
		if in.Jobs[k].ID == "" {
			b := make([]byte, 4)
			rand.Read(b)
			in.Jobs[k].ID = hex.EncodeToString(b)
		}
	}
	err := s.cfg.Update(func(c *config.Config) error {
		c.Jobs, c.Macros, c.Notify, c.Welcome, c.ChatFilter = in.Jobs, in.Macros, in.Notify, in.Welcome, in.ChatFilter
		return nil
	})
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.m.Audit(p.Name, "", "changed schedules, macros, notifications or filters")
	c := s.cfg.Get()
	writeJSON(w, settings{c.Jobs, c.Macros, c.Notify, c.Welcome, c.ChatFilter})
}

// ---- users and tokens ----

func (s *Server) listUsers(w http.ResponseWriter, r *http.Request, p principal) {
	type user struct {
		Name string      `json:"name"`
		Role config.Role `json:"role"`
	}
	out := []user{}
	for _, u := range s.cfg.Get().Users {
		out = append(out, user{u.Name, u.Role})
	}
	writeJSON(w, out)
}

func (s *Server) saveUser(w http.ResponseWriter, r *http.Request, p principal) {
	var in struct {
		Name     string      `json:"name"`
		Role     config.Role `json:"role"`
		Password string      `json:"password"`
	}
	if !decode(w, r, &in) {
		return
	}
	in.Name = strings.TrimSpace(in.Name)
	err := s.cfg.Update(func(c *config.Config) error {
		for k := range c.Users {
			if c.Users[k].Name == in.Name {
				if c.Users[k].Role == config.Admin && in.Role != config.Admin && countAdmins(c) == 1 {
					return fmt.Errorf("there must be at least one admin")
				}
				c.Users[k].Role = in.Role
				if in.Password != "" {
					h, err := newHash(in.Password)
					if err != nil {
						return err
					}
					c.Users[k].Hash = h
				}
				return nil
			}
		}
		h, err := newHash(in.Password)
		if err != nil {
			return err
		}
		c.Users = append(c.Users, config.User{Name: in.Name, Role: in.Role, Hash: h})
		return nil
	})
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.m.Audit(p.Name, "", "saved user "+in.Name+" ("+string(in.Role)+")")
	writeJSON(w, map[string]bool{"ok": true})
}

func newHash(password string) (string, error) {
	if len(password) < 8 {
		return "", fmt.Errorf("the password must be at least 8 characters")
	}
	return config.HashPassword(password)
}

func countAdmins(c *config.Config) int {
	n := 0
	for _, u := range c.Users {
		if u.Role == config.Admin {
			n++
		}
	}
	return n
}

func (s *Server) deleteUser(w http.ResponseWriter, r *http.Request, p principal) {
	name := r.PathValue("name")
	err := s.cfg.Update(func(c *config.Config) error {
		var keep []config.User
		for _, u := range c.Users {
			if u.Name != name {
				keep = append(keep, u)
			}
		}
		c.Users = keep
		if countAdmins(c) == 0 {
			return fmt.Errorf("there must be at least one admin")
		}
		return nil
	})
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.mu.Lock()
	for k, sess := range s.sessions {
		if sess.user == name {
			delete(s.sessions, k)
		}
	}
	s.mu.Unlock()
	s.m.Audit(p.Name, "", "deleted user "+name)
	writeJSON(w, map[string]bool{"ok": true})
}

func (s *Server) listTokens(w http.ResponseWriter, r *http.Request, p principal) {
	type token struct {
		Name string      `json:"name"`
		Role config.Role `json:"role"`
	}
	out := []token{}
	for _, t := range s.cfg.Get().Tokens {
		out = append(out, token{t.Name, t.Role})
	}
	writeJSON(w, out)
}

func (s *Server) newToken(w http.ResponseWriter, r *http.Request, p principal) {
	var in struct {
		Name string      `json:"name"`
		Role config.Role `json:"role"`
	}
	if !decode(w, r, &in) {
		return
	}
	token, hash, err := config.NewToken()
	if err == nil {
		err = s.cfg.Update(func(c *config.Config) error {
			for _, t := range c.Tokens {
				if t.Name == in.Name {
					return fmt.Errorf("a token named %q already exists", in.Name)
				}
			}
			c.Tokens = append(c.Tokens, config.Token{Name: in.Name, Role: in.Role, Hash: hash})
			return nil
		})
	}
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.m.Audit(p.Name, "", "created API token "+in.Name+" ("+string(in.Role)+")")
	writeJSON(w, map[string]string{"token": token}) // the only time it is shown
}

func (s *Server) deleteToken(w http.ResponseWriter, r *http.Request, p principal) {
	name := r.PathValue("name")
	err := s.cfg.Update(func(c *config.Config) error {
		var keep []config.Token
		for _, t := range c.Tokens {
			if t.Name != name {
				keep = append(keep, t)
			}
		}
		c.Tokens = keep
		return nil
	})
	if err != nil {
		fail(w, http.StatusBadRequest, err.Error())
		return
	}
	s.m.Audit(p.Name, "", "deleted API token "+name)
	writeJSON(w, map[string]bool{"ok": true})
}