package handler

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

	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5/pgtype"
	db "github.com/multica-ai/multica/server/pkg/db/generated"
)

// --- Response structs ---

type SkillResponse struct {
	ID          string `json:"id"`
	WorkspaceID string `json:"workspace_id"`
	Name        string `json:"name"`
	Description string `json:"description"`
	Content     string `json:"content"`
	Config      any    `json:"config"`
	CreatedBy   *string `json:"created_by"`
	CreatedAt   string `json:"created_at"`
	UpdatedAt   string `json:"updated_at"`
}

type SkillFileResponse struct {
	ID        string `json:"id"`
	SkillID   string `json:"skill_id"`
	Path      string `json:"path"`
	Content   string `json:"content"`
	CreatedAt string `json:"created_at"`
	UpdatedAt string `json:"updated_at"`
}

type SkillWithFilesResponse struct {
	SkillResponse
	Files []SkillFileResponse `json:"files"`
}

func skillToResponse(s db.Skill) SkillResponse {
	var config any
	if s.Config != nil {
		json.Unmarshal(s.Config, &config)
	}
	if config == nil {
		config = map[string]any{}
	}

	return SkillResponse{
		ID:          uuidToString(s.ID),
		WorkspaceID: uuidToString(s.WorkspaceID),
		Name:        s.Name,
		Description: s.Description,
		Content:     s.Content,
		Config:      config,
		CreatedBy:   uuidToPtr(s.CreatedBy),
		CreatedAt:   timestampToString(s.CreatedAt),
		UpdatedAt:   timestampToString(s.UpdatedAt),
	}
}

func skillFileToResponse(f db.SkillFile) SkillFileResponse {
	return SkillFileResponse{
		ID:        uuidToString(f.ID),
		SkillID:   uuidToString(f.SkillID),
		Path:      f.Path,
		Content:   f.Content,
		CreatedAt: timestampToString(f.CreatedAt),
		UpdatedAt: timestampToString(f.UpdatedAt),
	}
}

// --- Request structs ---

type CreateSkillRequest struct {
	Name        string                   `json:"name"`
	Description string                   `json:"description"`
	Content     string                   `json:"content"`
	Config      any                      `json:"config"`
	Files       []CreateSkillFileRequest `json:"files,omitempty"`
}

type CreateSkillFileRequest struct {
	Path    string `json:"path"`
	Content string `json:"content"`
}

type UpdateSkillRequest struct {
	Name        *string                  `json:"name"`
	Description *string                  `json:"description"`
	Content     *string                  `json:"content"`
	Config      any                      `json:"config"`
	Files       []CreateSkillFileRequest `json:"files,omitempty"`
}

type SetAgentSkillsRequest struct {
	SkillIDs []string `json:"skill_ids"`
}

// --- Helpers ---

// validateFilePath checks that a file path is safe (no traversal, no absolute paths).
func validateFilePath(p string) bool {
	if p == "" {
		return false
	}
	if filepath.IsAbs(p) {
		return false
	}
	cleaned := filepath.Clean(p)
	if strings.HasPrefix(cleaned, "..") {
		return false
	}
	return true
}

func (h *Handler) loadSkillForUser(w http.ResponseWriter, r *http.Request, id string) (db.Skill, bool) {
	skill, err := h.Queries.GetSkill(r.Context(), parseUUID(id))
	if err != nil {
		if isNotFound(err) {
			writeError(w, http.StatusNotFound, "skill not found")
		} else {
			writeError(w, http.StatusInternalServerError, "failed to load skill")
		}
		return skill, false
	}
	if _, ok := h.requireWorkspaceMember(w, r, uuidToString(skill.WorkspaceID), "skill not found"); !ok {
		return skill, false
	}
	return skill, true
}

// --- Skill CRUD ---

func (h *Handler) ListSkills(w http.ResponseWriter, r *http.Request) {
	workspaceID := resolveWorkspaceID(r)
	if _, ok := h.requireWorkspaceMember(w, r, workspaceID, "workspace not found"); !ok {
		return
	}

	skills, err := h.Queries.ListSkillsByWorkspace(r.Context(), parseUUID(workspaceID))
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list skills")
		return
	}

	resp := make([]SkillResponse, len(skills))
	for i, s := range skills {
		resp[i] = skillToResponse(s)
	}

	writeJSON(w, http.StatusOK, resp)
}

func (h *Handler) GetSkill(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	skill, ok := h.loadSkillForUser(w, r, id)
	if !ok {
		return
	}

	files, err := h.Queries.ListSkillFiles(r.Context(), skill.ID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list skill files")
		return
	}

	fileResps := make([]SkillFileResponse, len(files))
	for i, f := range files {
		fileResps[i] = skillFileToResponse(f)
	}

	writeJSON(w, http.StatusOK, SkillWithFilesResponse{
		SkillResponse: skillToResponse(skill),
		Files:         fileResps,
	})
}

func (h *Handler) CreateSkill(w http.ResponseWriter, r *http.Request) {
	workspaceID := resolveWorkspaceID(r)
	if _, ok := h.requireWorkspaceRole(w, r, workspaceID, "workspace not found", "owner", "admin"); !ok {
		return
	}

	creatorID, ok := requireUserID(w, r)
	if !ok {
		return
	}

	var req CreateSkillRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	if req.Name == "" {
		writeError(w, http.StatusBadRequest, "name is required")
		return
	}

	for _, f := range req.Files {
		if !validateFilePath(f.Path) {
			writeError(w, http.StatusBadRequest, "invalid file path: "+f.Path)
			return
		}
	}

	config, _ := json.Marshal(req.Config)
	if req.Config == nil {
		config = []byte("{}")
	}

	tx, err := h.TxStarter.Begin(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to start transaction")
		return
	}
	defer tx.Rollback(r.Context())

	qtx := h.Queries.WithTx(tx)

	skill, err := qtx.CreateSkill(r.Context(), db.CreateSkillParams{
		WorkspaceID: parseUUID(workspaceID),
		Name:        req.Name,
		Description: req.Description,
		Content:     req.Content,
		Config:      config,
		CreatedBy:   parseUUID(creatorID),
	})
	if err != nil {
		if isUniqueViolation(err) {
			writeError(w, http.StatusConflict, "a skill with this name already exists")
			return
		}
		writeError(w, http.StatusInternalServerError, "failed to create skill: "+err.Error())
		return
	}

	fileResps := make([]SkillFileResponse, 0, len(req.Files))
	for _, f := range req.Files {
		sf, err := qtx.UpsertSkillFile(r.Context(), db.UpsertSkillFileParams{
			SkillID: skill.ID,
			Path:    f.Path,
			Content: f.Content,
		})
		if err != nil {
			writeError(w, http.StatusInternalServerError, "failed to create skill file: "+err.Error())
			return
		}
		fileResps = append(fileResps, skillFileToResponse(sf))
	}

	if err := tx.Commit(r.Context()); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to commit")
		return
	}

	resp := SkillWithFilesResponse{
		SkillResponse: skillToResponse(skill),
		Files:         fileResps,
	}
	h.publish("skill:created", workspaceID, "member", creatorID, map[string]any{"skill": resp})
	writeJSON(w, http.StatusCreated, resp)
}

func (h *Handler) UpdateSkill(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	skill, ok := h.loadSkillForUser(w, r, id)
	if !ok {
		return
	}
	if _, ok := h.requireWorkspaceRole(w, r, uuidToString(skill.WorkspaceID), "skill not found", "owner", "admin"); !ok {
		return
	}

	var req UpdateSkillRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	for _, f := range req.Files {
		if !validateFilePath(f.Path) {
			writeError(w, http.StatusBadRequest, "invalid file path: "+f.Path)
			return
		}
	}

	tx, err := h.TxStarter.Begin(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to start transaction")
		return
	}
	defer tx.Rollback(r.Context())

	qtx := h.Queries.WithTx(tx)

	params := db.UpdateSkillParams{
		ID: parseUUID(id),
	}
	if req.Name != nil {
		params.Name = pgtype.Text{String: *req.Name, Valid: true}
	}
	if req.Description != nil {
		params.Description = pgtype.Text{String: *req.Description, Valid: true}
	}
	if req.Content != nil {
		params.Content = pgtype.Text{String: *req.Content, Valid: true}
	}
	if req.Config != nil {
		config, _ := json.Marshal(req.Config)
		params.Config = config
	}

	skill, err = qtx.UpdateSkill(r.Context(), params)
	if err != nil {
		if isUniqueViolation(err) {
			writeError(w, http.StatusConflict, "a skill with this name already exists")
			return
		}
		writeError(w, http.StatusInternalServerError, "failed to update skill: "+err.Error())
		return
	}

	// If files are provided, replace all files.
	var fileResps []SkillFileResponse
	if req.Files != nil {
		if err := qtx.DeleteSkillFilesBySkill(r.Context(), skill.ID); err != nil {
			writeError(w, http.StatusInternalServerError, "failed to delete old skill files")
			return
		}
		fileResps = make([]SkillFileResponse, 0, len(req.Files))
		for _, f := range req.Files {
			sf, err := qtx.UpsertSkillFile(r.Context(), db.UpsertSkillFileParams{
				SkillID: skill.ID,
				Path:    f.Path,
				Content: f.Content,
			})
			if err != nil {
				writeError(w, http.StatusInternalServerError, "failed to upsert skill file: "+err.Error())
				return
			}
			fileResps = append(fileResps, skillFileToResponse(sf))
		}
	} else {
		files, _ := qtx.ListSkillFiles(r.Context(), skill.ID)
		fileResps = make([]SkillFileResponse, len(files))
		for i, f := range files {
			fileResps[i] = skillFileToResponse(f)
		}
	}

	if err := tx.Commit(r.Context()); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to commit")
		return
	}

	resp := SkillWithFilesResponse{
		SkillResponse: skillToResponse(skill),
		Files:         fileResps,
	}
	h.publish("skill:updated", resolveWorkspaceID(r), "member", requestUserID(r), map[string]any{"skill": resp})
	writeJSON(w, http.StatusOK, resp)
}

func (h *Handler) DeleteSkill(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	skill, ok := h.loadSkillForUser(w, r, id)
	if !ok {
		return
	}
	if _, ok := h.requireWorkspaceRole(w, r, uuidToString(skill.WorkspaceID), "skill not found", "owner", "admin"); !ok {
		return
	}

	if err := h.Queries.DeleteSkill(r.Context(), parseUUID(id)); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to delete skill")
		return
	}
	h.publish("skill:deleted", uuidToString(skill.WorkspaceID), "member", requestUserID(r), map[string]any{"skill_id": id})
	w.WriteHeader(http.StatusNoContent)
}

// --- Skill File endpoints ---

func (h *Handler) ListSkillFiles(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	skill, ok := h.loadSkillForUser(w, r, id)
	if !ok {
		return
	}

	files, err := h.Queries.ListSkillFiles(r.Context(), skill.ID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list skill files")
		return
	}

	resp := make([]SkillFileResponse, len(files))
	for i, f := range files {
		resp[i] = skillFileToResponse(f)
	}
	writeJSON(w, http.StatusOK, resp)
}

func (h *Handler) UpsertSkillFile(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	skill, ok := h.loadSkillForUser(w, r, id)
	if !ok {
		return
	}
	if _, ok := h.requireWorkspaceRole(w, r, uuidToString(skill.WorkspaceID), "skill not found", "owner", "admin"); !ok {
		return
	}

	var req CreateSkillFileRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	if !validateFilePath(req.Path) {
		writeError(w, http.StatusBadRequest, "invalid file path")
		return
	}

	sf, err := h.Queries.UpsertSkillFile(r.Context(), db.UpsertSkillFileParams{
		SkillID: skill.ID,
		Path:    req.Path,
		Content: req.Content,
	})
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to upsert skill file: "+err.Error())
		return
	}

	writeJSON(w, http.StatusOK, skillFileToResponse(sf))
}

func (h *Handler) DeleteSkillFile(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	skill, ok := h.loadSkillForUser(w, r, id)
	if !ok {
		return
	}
	if _, ok := h.requireWorkspaceRole(w, r, uuidToString(skill.WorkspaceID), "skill not found", "owner", "admin"); !ok {
		return
	}

	fileID := chi.URLParam(r, "fileId")
	if err := h.Queries.DeleteSkillFile(r.Context(), parseUUID(fileID)); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to delete skill file")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// --- Agent-Skill junction ---

func (h *Handler) ListAgentSkills(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	agent, ok := h.loadAgentForUser(w, r, id)
	if !ok {
		return
	}

	skills, err := h.Queries.ListAgentSkills(r.Context(), agent.ID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list agent skills")
		return
	}

	resp := make([]SkillResponse, len(skills))
	for i, s := range skills {
		resp[i] = skillToResponse(s)
	}
	writeJSON(w, http.StatusOK, resp)
}

func (h *Handler) SetAgentSkills(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	agent, ok := h.loadAgentForUser(w, r, id)
	if !ok {
		return
	}
	if _, ok := h.requireWorkspaceRole(w, r, uuidToString(agent.WorkspaceID), "agent not found", "owner", "admin"); !ok {
		return
	}

	var req SetAgentSkillsRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	tx, err := h.TxStarter.Begin(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to start transaction")
		return
	}
	defer tx.Rollback(r.Context())

	qtx := h.Queries.WithTx(tx)

	if err := qtx.RemoveAllAgentSkills(r.Context(), agent.ID); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to clear agent skills")
		return
	}

	for _, skillID := range req.SkillIDs {
		if err := qtx.AddAgentSkill(r.Context(), db.AddAgentSkillParams{
			AgentID: agent.ID,
			SkillID: parseUUID(skillID),
		}); err != nil {
			writeError(w, http.StatusInternalServerError, "failed to add agent skill: "+err.Error())
			return
		}
	}

	if err := tx.Commit(r.Context()); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to commit")
		return
	}

	// Return the updated skills list.
	skills, err := h.Queries.ListAgentSkills(r.Context(), agent.ID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list agent skills")
		return
	}

	resp := make([]SkillResponse, len(skills))
	for i, s := range skills {
		resp[i] = skillToResponse(s)
	}
	h.publish("agent:status", uuidToString(agent.WorkspaceID), "member", requestUserID(r), map[string]any{"agent_id": uuidToString(agent.ID), "skills": resp})
	writeJSON(w, http.StatusOK, resp)
}