package api

import (
	"encoding/json"
	"log"
	"net/http"

	"github.com/go-chi/chi/v5"
	"github.com/google/uuid"

	"github.com/vasyakrg/dns-autoresolver/internal/provider"
	"github.com/vasyakrg/dns-autoresolver/internal/store/dto"
)

func decodeBody(w http.ResponseWriter, r *http.Request, v any) bool {
	r.Body = http.MaxBytesReader(w, r.Body, 1<<20) // 1 MiB
	if err := json.NewDecoder(r.Body).Decode(v); err != nil {
		writeErr(w, http.StatusBadRequest, "invalid request body")
		return false
	}
	return true
}

// --- accounts ---

func (a *API) handleCreateAccount(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	var req accountRequest
	if !decodeBody(w, r, &req) {
		return
	}
	if req.Provider == "" || req.Secret == "" {
		writeErr(w, http.StatusBadRequest, "provider and secret are required")
		return
	}
	secretEnc, err := a.Cipher.Encrypt([]byte(req.Secret))
	if err != nil {
		log.Printf("api: encrypt secret failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	acc, err := a.Store.CreateAccount(r.Context(), pid, req.Provider, secretEnc, req.Comment)
	if err != nil {
		log.Printf("api: create account failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	writeJSON(w, http.StatusCreated, toAccountResponse(acc))
}

func (a *API) handleListAccounts(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	accs, err := a.Store.ListAccounts(r.Context(), pid)
	if err != nil {
		log.Printf("api: list accounts failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	resp := make([]accountResponse, 0, len(accs))
	for _, acc := range accs {
		resp = append(resp, toAccountResponse(acc))
	}
	writeJSON(w, http.StatusOK, resp)
}

func (a *API) handleDeleteAccount(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	aid, err := uuid.Parse(chi.URLParam(r, "aid"))
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid account id")
		return
	}
	if err := a.Store.DeleteAccount(r.Context(), aid, pid); err != nil {
		log.Printf("api: delete account failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// handleImportZones lists zones from the provider for the given account and
// creates one domain per zone (template_id left unset).
func (a *API) handleImportZones(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	aid, err := uuid.Parse(chi.URLParam(r, "aid"))
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid account id")
		return
	}
	acc, err := a.Store.GetAccount(r.Context(), aid, pid)
	if err != nil {
		log.Printf("api: import: get account failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	secret, err := a.Cipher.Decrypt(acc.SecretEnc)
	if err != nil {
		log.Printf("api: import: decrypt secret failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	p, err := a.Reg.ByName(acc.Provider)
	if err != nil {
		log.Printf("api: import: unknown provider: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	zones, err := p.ListZones(r.Context(), provider.Credentials{Secret: string(secret)})
	if err != nil {
		log.Printf("api: import: list zones failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	// Imported atomically: either every zone becomes a domain or none does,
	// so a mid-batch provider/DB error never leaves a partial import behind.
	doms, err := a.Store.ImportDomains(r.Context(), pid, aid, zones)
	if err != nil {
		log.Printf("api: import: create domains failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	created := make([]domainResponse, 0, len(doms))
	for _, d := range doms {
		created = append(created, toDomainResponse(d))
	}
	writeJSON(w, http.StatusCreated, created)
}

// --- templates ---

func (a *API) handleCreateTemplate(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	var req templateRequest
	if !decodeBody(w, r, &req) {
		return
	}
	if req.Name == "" {
		writeErr(w, http.StatusBadRequest, "name is required")
		return
	}
	doc := dto.TemplateDoc{Records: req.Records}
	tpl, err := a.Store.CreateTemplate(r.Context(), pid, req.Name, doc)
	if err != nil {
		log.Printf("api: create template failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	writeJSON(w, http.StatusCreated, toTemplateResponse(tpl))
}

func (a *API) handleListTemplates(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	tpls, err := a.Store.ListTemplates(r.Context(), pid)
	if err != nil {
		log.Printf("api: list templates failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	resp := make([]templateResponse, 0, len(tpls))
	for _, t := range tpls {
		resp = append(resp, toTemplateResponse(t))
	}
	writeJSON(w, http.StatusOK, resp)
}

func (a *API) handleUpdateTemplate(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	tid, err := uuid.Parse(chi.URLParam(r, "tid"))
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid template id")
		return
	}
	var req templateRequest
	if !decodeBody(w, r, &req) {
		return
	}
	if req.Name == "" {
		writeErr(w, http.StatusBadRequest, "name is required")
		return
	}
	doc := dto.TemplateDoc{Records: req.Records}
	tpl, err := a.Store.UpdateTemplate(r.Context(), tid, pid, req.Name, doc)
	if err != nil {
		log.Printf("api: update template failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	writeJSON(w, http.StatusOK, toTemplateResponse(tpl))
}

func (a *API) handleDeleteTemplate(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	tid, err := uuid.Parse(chi.URLParam(r, "tid"))
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid template id")
		return
	}
	if err := a.Store.DeleteTemplate(r.Context(), tid, pid); err != nil {
		log.Printf("api: delete template failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// --- domains ---

func (a *API) handleCreateDomain(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	var req domainRequest
	if !decodeBody(w, r, &req) {
		return
	}
	accID, err := uuid.Parse(req.ProviderAccountID)
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid providerAccountId")
		return
	}
	if req.ZoneName == "" || req.ZoneID == "" {
		writeErr(w, http.StatusBadRequest, "zoneName and zoneId are required")
		return
	}
	templateID, ok := parseOptionalUUID(req.TemplateID)
	if !ok {
		writeErr(w, http.StatusBadRequest, "invalid templateId")
		return
	}

	// Tenant isolation: the account (and template, if given) must belong to
	// this project — otherwise a caller could attach a domain to another
	// tenant's provider account or DNS template.
	if _, err := a.Store.GetAccount(r.Context(), accID, pid); err != nil {
		writeErr(w, http.StatusNotFound, "provider account not found")
		return
	}
	if templateID != nil {
		if _, err := a.Store.GetTemplate(r.Context(), *templateID, pid); err != nil {
			writeErr(w, http.StatusNotFound, "template not found")
			return
		}
	}

	dom, err := a.Store.CreateDomain(r.Context(), pid, accID, req.ZoneName, req.ZoneID, templateID)
	if err != nil {
		log.Printf("api: create domain failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	writeJSON(w, http.StatusCreated, toDomainResponse(dom))
}

func (a *API) handleListDomains(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	doms, err := a.Store.ListDomains(r.Context(), pid)
	if err != nil {
		log.Printf("api: list domains failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	resp := make([]domainResponse, 0, len(doms))
	for _, d := range doms {
		resp = append(resp, toDomainResponse(d))
	}
	writeJSON(w, http.StatusOK, resp)
}

// handleSetDomainTemplate binds (or clears) the DNS template used to
// check/apply a domain — this is what makes an imported domain (which
// starts with template_id=NULL) checkable, closing the import→check loop.
func (a *API) handleSetDomainTemplate(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	did, err := uuid.Parse(chi.URLParam(r, "did"))
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid domain id")
		return
	}
	var req updateDomainTemplateRequest
	if !decodeBody(w, r, &req) {
		return
	}
	templateID, ok := parseOptionalUUID(req.TemplateID)
	if !ok {
		writeErr(w, http.StatusBadRequest, "invalid templateId")
		return
	}

	dom, err := a.Store.SetDomainTemplate(r.Context(), did, pid, templateID)
	if err != nil {
		// Either the domain itself or the (scoped) template wasn't found in
		// this project — treat both as 404 rather than leak which one.
		writeErr(w, http.StatusNotFound, "domain or template not found")
		return
	}
	writeJSON(w, http.StatusOK, toDomainResponse(dom))
}

func (a *API) handleDeleteDomain(w http.ResponseWriter, r *http.Request) {
	// pid is guaranteed present and owned by the caller — RequireProjectAccess
	// validated it before this handler ever runs.
	pid, _ := projectIDFrom(r.Context())
	did, err := uuid.Parse(chi.URLParam(r, "did"))
	if err != nil {
		writeErr(w, http.StatusBadRequest, "invalid domain id")
		return
	}
	if err := a.Store.DeleteDomain(r.Context(), did, pid); err != nil {
		log.Printf("api: delete domain failed: %v", err)
		writeErr(w, http.StatusInternalServerError, "internal error")
		return
	}
	w.WriteHeader(http.StatusNoContent)
}