package handlers

import (
	"encoding/json"
	"net/http"
	"path/filepath"
	"strconv"

	"github.com/go-chi/chi/v5"
	"xorm.io/xorm"

	"github.com/forgeo/forgebucket/internal/api/middleware"
	"github.com/forgeo/forgebucket/internal/config"
	"github.com/forgeo/forgebucket/internal/models"
)

type WorkspaceHandler struct {
	db  *xorm.Engine
	cfg *config.Config
}

func NewWorkspaceHandler(db *xorm.Engine, cfg *config.Config) *WorkspaceHandler {
	return &WorkspaceHandler{db: db, cfg: cfg}
}

// ── Response shapes ───────────────────────────────────────────────────────────

type workspaceResponse struct {
	models.Workspace
	MemberCount int    `json:"memberCount"`
	RepoCount   int    `json:"repoCount"`
	MyRole      string `json:"myRole"` // caller's role, empty if not a member
}

// ── List ──────────────────────────────────────────────────────────────────────

// ListWorkspaces returns all workspaces the current user belongs to.
func (h *WorkspaceHandler) ListWorkspaces(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.UserIDFromContext(r.Context())

	var memberships []models.WorkspaceMember
	h.db.Where("user_id = ?", userID).Find(&memberships)

	if len(memberships) == 0 {
		jsonOK(w, []workspaceResponse{})
		return
	}

	wsIDs := make([]int64, len(memberships))
	roleByWS := map[int64]string{}
	for i, m := range memberships {
		wsIDs[i] = m.WorkspaceID
		roleByWS[m.WorkspaceID] = string(m.Role)
	}

	var workspaces []models.Workspace
	h.db.In("id", wsIDs).Find(&workspaces)

	result := make([]workspaceResponse, len(workspaces))
	for i, ws := range workspaces {
		memberCount, _ := h.db.Where("workspace_id = ?", ws.ID).Count(&models.WorkspaceMember{})
		repoCount, _ := h.db.Where("workspace_id = ?", ws.ID).Count(&models.Repository{})
		result[i] = workspaceResponse{
			Workspace:   ws,
			MemberCount: int(memberCount),
			RepoCount:   int(repoCount),
			MyRole:      roleByWS[ws.ID],
		}
	}
	jsonOK(w, result)
}

// ── Create ────────────────────────────────────────────────────────────────────

func (h *WorkspaceHandler) CreateWorkspace(w http.ResponseWriter, r *http.Request) {
	userID, _ := middleware.UserIDFromContext(r.Context())

	var body struct {
		Handle      string `json:"handle"`
		DisplayName string `json:"displayName"`
		Description string `json:"description"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		jsonError(w, "invalid request body", http.StatusBadRequest)
		return
	}
	if body.Handle == "" {
		jsonError(w, "handle is required", http.StatusBadRequest)
		return
	}
	if !isValidHandle(body.Handle) {
		jsonError(w, "handle may only contain letters, numbers, hyphens, and underscores", http.StatusBadRequest)
		return
	}

	// Handle must not collide with any username or existing workspace handle.
	var existingUser models.User
	if found, _ := h.db.Where("username = ?", body.Handle).Get(&existingUser); found {
		jsonError(w, "handle is already taken by a user", http.StatusConflict)
		return
	}
	var existingWS models.Workspace
	if found, _ := h.db.Where("handle = ?", body.Handle).Get(&existingWS); found {
		jsonError(w, "handle is already taken by a workspace", http.StatusConflict)
		return
	}

	ws := &models.Workspace{
		Handle:      body.Handle,
		DisplayName: body.DisplayName,
		Description: body.Description,
		CreatedBy:   userID,
	}
	if _, err := h.db.Insert(ws); err != nil {
		jsonError(w, "could not create workspace", http.StatusInternalServerError)
		return
	}

	// Creator becomes owner automatically.
	var creator models.User
	h.db.ID(userID).Cols("username").Get(&creator)
	member := &models.WorkspaceMember{
		WorkspaceID: ws.ID,
		UserID:      userID,
		Username:    creator.Username,
		Role:        models.WorkspaceRoleOwner,
	}
	h.db.Insert(member) //nolint:errcheck

	resp := workspaceResponse{Workspace: *ws, MemberCount: 1, MyRole: string(models.WorkspaceRoleOwner)}
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(resp) //nolint:errcheck
}

// ── Get ───────────────────────────────────────────────────────────────────────

func (h *WorkspaceHandler) GetWorkspace(w http.ResponseWriter, r *http.Request) {
	ws, myRole, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	memberCount, _ := h.db.Where("workspace_id = ?", ws.ID).Count(&models.WorkspaceMember{})
	repoCount, _ := h.db.Where("workspace_id = ?", ws.ID).Count(&models.Repository{})
	jsonOK(w, workspaceResponse{Workspace: *ws, MemberCount: int(memberCount), RepoCount: int(repoCount), MyRole: myRole})
}

// ── Update ────────────────────────────────────────────────────────────────────

func (h *WorkspaceHandler) UpdateWorkspace(w http.ResponseWriter, r *http.Request) {
	ws, myRole, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	if myRole != string(models.WorkspaceRoleOwner) && myRole != string(models.WorkspaceRoleAdmin) {
		jsonError(w, "admin or owner required", http.StatusForbidden)
		return
	}

	var body struct {
		DisplayName *string `json:"displayName"`
		Description *string `json:"description"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		jsonError(w, "invalid request body", http.StatusBadRequest)
		return
	}
	cols := []string{}
	if body.DisplayName != nil {
		ws.DisplayName = *body.DisplayName
		cols = append(cols, "display_name")
	}
	if body.Description != nil {
		ws.Description = *body.Description
		cols = append(cols, "description")
	}
	if len(cols) > 0 {
		h.db.ID(ws.ID).Cols(cols...).Update(ws) //nolint:errcheck
	}
	jsonOK(w, ws)
}

// ── Delete ────────────────────────────────────────────────────────────────────

func (h *WorkspaceHandler) DeleteWorkspace(w http.ResponseWriter, r *http.Request) {
	ws, myRole, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	if myRole != string(models.WorkspaceRoleOwner) {
		jsonError(w, "only the workspace owner can delete it", http.StatusForbidden)
		return
	}
	// Refuse if the workspace still has repos.
	count, _ := h.db.Where("workspace_id = ?", ws.ID).Count(&models.Repository{})
	if count > 0 {
		jsonError(w, "delete or transfer all repositories before deleting the workspace", http.StatusConflict)
		return
	}
	h.db.Where("workspace_id = ?", ws.ID).Delete(&models.WorkspaceMember{}) //nolint:errcheck
	h.db.ID(ws.ID).Delete(&models.Workspace{})                               //nolint:errcheck
	w.WriteHeader(http.StatusNoContent)
}

// ── Repos in workspace ────────────────────────────────────────────────────────

func (h *WorkspaceHandler) ListRepos(w http.ResponseWriter, r *http.Request) {
	ws, _, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	var repos []models.Repository
	h.db.Where("workspace_id = ?", ws.ID).Find(&repos)
	if repos == nil {
		repos = []models.Repository{}
	}
	// Return the same enriched shape that the repo list uses.
	type wsRepoResponse struct {
		models.Repository
		OwnerName string `json:"ownerName"`
	}
	result := make([]wsRepoResponse, len(repos))
	for i, r := range repos {
		result[i] = wsRepoResponse{Repository: r, OwnerName: ws.Handle}
	}
	jsonOK(w, result)
}

// ── Members ───────────────────────────────────────────────────────────────────

func (h *WorkspaceHandler) ListMembers(w http.ResponseWriter, r *http.Request) {
	ws, _, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	var members []models.WorkspaceMember
	h.db.Where("workspace_id = ?", ws.ID).Find(&members)
	if members == nil {
		members = []models.WorkspaceMember{}
	}
	jsonOK(w, members)
}

func (h *WorkspaceHandler) AddMember(w http.ResponseWriter, r *http.Request) {
	ws, myRole, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	if myRole != string(models.WorkspaceRoleOwner) && myRole != string(models.WorkspaceRoleAdmin) {
		jsonError(w, "admin or owner required", http.StatusForbidden)
		return
	}

	var body struct {
		Username string `json:"username"`
		Role     string `json:"role"` // "admin" | "member"
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		jsonError(w, "invalid request body", http.StatusBadRequest)
		return
	}
	role := models.WorkspaceRole(body.Role)
	if role != models.WorkspaceRoleAdmin && role != models.WorkspaceRoleMember {
		role = models.WorkspaceRoleMember
	}

	var user models.User
	if found, _ := h.db.Where("username = ?", body.Username).Get(&user); !found {
		jsonError(w, "user not found", http.StatusNotFound)
		return
	}

	// Idempotent: update role if already a member.
	var existing models.WorkspaceMember
	if found, _ := h.db.Where("workspace_id = ? AND user_id = ?", ws.ID, user.ID).Get(&existing); found {
		existing.Role = role
		h.db.ID(existing.ID).Cols("role").Update(&existing) //nolint:errcheck
		jsonOK(w, existing)
		return
	}

	member := &models.WorkspaceMember{
		WorkspaceID: ws.ID,
		UserID:      user.ID,
		Username:    user.Username,
		Role:        role,
	}
	if _, err := h.db.Insert(member); err != nil {
		jsonError(w, "could not add member", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(member) //nolint:errcheck
}

func (h *WorkspaceHandler) UpdateMember(w http.ResponseWriter, r *http.Request) {
	ws, myRole, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	if myRole != string(models.WorkspaceRoleOwner) && myRole != string(models.WorkspaceRoleAdmin) {
		jsonError(w, "admin or owner required", http.StatusForbidden)
		return
	}

	targetUsername := chi.URLParam(r, "username")
	var body struct{ Role string `json:"role"` }
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		jsonError(w, "invalid request body", http.StatusBadRequest)
		return
	}

	var target models.User
	if found, _ := h.db.Where("username = ?", targetUsername).Get(&target); !found {
		jsonError(w, "user not found", http.StatusNotFound)
		return
	}
	var member models.WorkspaceMember
	if found, _ := h.db.Where("workspace_id = ? AND user_id = ?", ws.ID, target.ID).Get(&member); !found {
		jsonError(w, "member not found", http.StatusNotFound)
		return
	}
	// Cannot demote the last owner.
	if member.Role == models.WorkspaceRoleOwner && models.WorkspaceRole(body.Role) != models.WorkspaceRoleOwner {
		count, _ := h.db.Where("workspace_id = ? AND role = 'owner'", ws.ID).Count(&models.WorkspaceMember{})
		if count <= 1 {
			jsonError(w, "workspace must have at least one owner", http.StatusConflict)
			return
		}
	}
	member.Role = models.WorkspaceRole(body.Role)
	h.db.ID(member.ID).Cols("role").Update(&member) //nolint:errcheck
	jsonOK(w, member)
}

func (h *WorkspaceHandler) RemoveMember(w http.ResponseWriter, r *http.Request) {
	ws, myRole, ok := h.resolveWorkspace(w, r)
	if !ok {
		return
	}
	callerID, _ := middleware.UserIDFromContext(r.Context())
	targetUsername := chi.URLParam(r, "username")

	var target models.User
	if found, _ := h.db.Where("username = ?", targetUsername).Get(&target); !found {
		jsonError(w, "user not found", http.StatusNotFound)
		return
	}

	// Members can remove themselves; admins/owners can remove others.
	if target.ID != callerID {
		if myRole != string(models.WorkspaceRoleOwner) && myRole != string(models.WorkspaceRoleAdmin) {
			jsonError(w, "admin or owner required", http.StatusForbidden)
			return
		}
	}

	var member models.WorkspaceMember
	if found, _ := h.db.Where("workspace_id = ? AND user_id = ?", ws.ID, target.ID).Get(&member); !found {
		jsonError(w, "member not found", http.StatusNotFound)
		return
	}
	if member.Role == models.WorkspaceRoleOwner {
		count, _ := h.db.Where("workspace_id = ? AND role = 'owner'", ws.ID).Count(&models.WorkspaceMember{})
		if count <= 1 {
			jsonError(w, "cannot remove the last owner", http.StatusConflict)
			return
		}
	}
	h.db.ID(member.ID).Delete(&models.WorkspaceMember{}) //nolint:errcheck
	w.WriteHeader(http.StatusNoContent)
}

// ── Helpers ───────────────────────────────────────────────────────────────────

func (h *WorkspaceHandler) resolveWorkspace(w http.ResponseWriter, r *http.Request) (*models.Workspace, string, bool) {
	handle := chi.URLParam(r, "handle")
	var ws models.Workspace
	if found, _ := h.db.Where("handle = ?", handle).Get(&ws); !found {
		jsonError(w, "workspace not found", http.StatusNotFound)
		return nil, "", false
	}
	userID, _ := middleware.UserIDFromContext(r.Context())
	var member models.WorkspaceMember
	myRole := ""
	if found, _ := h.db.Where("workspace_id = ? AND user_id = ?", ws.ID, userID).Get(&member); found {
		myRole = string(member.Role)
	}
	return &ws, myRole, true
}

// diskPathForWorkspaceRepo returns the on-disk bare repo path for workspace-owned repos.
func diskPathForWorkspaceRepo(repoRoot string, workspaceID int64, repoName string) string {
	return filepath.Join(repoRoot, "ws_"+strconv.FormatInt(workspaceID, 10), repoName+".git")
}

func isValidHandle(h string) bool {
	if len(h) == 0 || len(h) > 64 {
		return false
	}
	for _, c := range h {
		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
			(c >= '0' && c <= '9') || c == '-' || c == '_') {
			return false
		}
	}
	return true
}