package web

import (
	"context"
	"slices"
	"sync"
	"time"

	"git.zio.sh/cs2/simpleadmin-web/internal/store"
)

// staffIndex is SimpleAdmin's admins and groups for this server, merged the way CounterStrikeSharp's
// AdminManager sees them: an admin's permissions are their own @flags plus their groups' flags, and
// their immunity is the highest of their own and their groups'.
type staffIndex struct {
	groups  []store.Group
	byName  map[string]*store.Group
	admins  []store.Admin
	bySteam map[string]*store.Admin
}

type staffCache struct {
	st  *store.Store
	ttl time.Duration

	mu      sync.Mutex
	idx     *staffIndex
	fetched time.Time
}

func (c *staffCache) get(ctx context.Context) (*staffIndex, error) {
	c.mu.Lock()
	defer c.mu.Unlock()
	if c.idx != nil && time.Since(c.fetched) < c.ttl {
		return c.idx, nil
	}
	groups, err := c.st.Groups(ctx)
	if err != nil {
		return nil, err
	}
	admins, err := c.st.Admins(ctx)
	if err != nil {
		return nil, err
	}
	idx := &staffIndex{groups: groups, admins: admins, byName: map[string]*store.Group{}, bySteam: map[string]*store.Admin{}}
	for i := range idx.groups {
		idx.byName[idx.groups[i].Name] = &idx.groups[i]
	}
	for i := range idx.admins {
		idx.bySteam[idx.admins[i].SteamID] = &idx.admins[i]
	}
	c.idx, c.fetched = idx, time.Now()
	return idx, nil
}

func (c *staffCache) invalidate() {
	c.mu.Lock()
	c.idx = nil
	c.mu.Unlock()
}

// flags returns an admin's effective permissions.
func (x *staffIndex) flags(a *store.Admin) []string {
	out := slices.Clone(a.Flags)
	for _, g := range a.Groups {
		if grp, ok := x.byName[g]; ok {
			for _, f := range grp.Flags {
				if !slices.Contains(out, f) {
					out = append(out, f)
				}
			}
		}
	}
	return out
}

// immunity returns a player's effective immunity, 0 for non-staff.
func (x *staffIndex) immunity(steamid string) int {
	a, ok := x.bySteam[steamid]
	if !ok {
		return 0
	}
	imm := a.Immunity
	for _, g := range a.Groups {
		if grp, ok := x.byName[g]; ok {
			imm = max(imm, grp.Immunity)
		}
	}
	return imm
}

// primaryGroup is the admin's highest-immunity group that exists, or "".
func (x *staffIndex) primaryGroup(a *store.Admin) string {
	best, bestImm := "", -1
	for _, g := range a.Groups {
		if grp, ok := x.byName[g]; ok && grp.Immunity > bestImm {
			best, bestImm = g, grp.Immunity
		}
	}
	return best
}

// groupIndex is a group's position, used to pick a stable fallback colour.
func (x *staffIndex) groupIndex(name string) int {
	for i, g := range x.groups {
		if g.Name == name {
			return i
		}
	}
	return 0
}

// Identity is a signed-in staff member.
type Identity struct {
	SteamID  string
	Name     string
	Flags    []string
	Immunity int
	RowID    int64
}

// Has reports whether the identity holds a permission. @css/root grants everything.
func (id *Identity) Has(flag string) bool {
	return slices.Contains(id.Flags, "@css/root") || slices.Contains(id.Flags, flag)
}

// CanTarget follows CounterStrikeSharp: you can act on players whose immunity isn't above yours.
// Nobody acts on themselves through the panel.
func (id *Identity) CanTarget(x *staffIndex, steamid string) bool {
	if steamid == id.SteamID {
		return false
	}
	return x.immunity(steamid) <= id.Immunity
}

// rankView is how a rank is shown to the browser.
type rankView struct {
	Name      string `json:"name"`
	Label     string `json:"label"`
	Color     string `json:"color"`
	Supporter bool   `json:"supporter,omitempty"`
}

func (s *Server) rankOf(x *staffIndex, steamid string) *rankView {
	a, ok := x.bySteam[steamid]
	if !ok {
		return nil
	}
	g := x.primaryGroup(a)
	if g == "" {
		return &rankView{Label: "Staff", Color: "#8a91a0"}
	}
	r := s.site.rank(g, x.groupIndex(g))
	return &rankView{Name: g, Label: r.Label, Color: r.Color, Supporter: r.Supporter}
}

// isStaff is true for admins whose rank isn't a supporter rank.
func (s *Server) isStaff(x *staffIndex, steamid string) bool {
	r := s.rankOf(x, steamid)
	return r != nil && !r.Supporter
}