package adminapi

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

	"github.com/iceBear67/simplepages/api"
	"github.com/iceBear67/simplepages/internal/cas"
	"github.com/iceBear67/simplepages/internal/httpx"
	"github.com/iceBear67/simplepages/internal/pathutil"
	"github.com/iceBear67/simplepages/internal/store"
)

// Caps on the deployment metadata a CI job may attach. Generous enough for a
// commit sha, a branch, a run URL and an actor; small enough that the column
// cannot become a place to store things.
const (
	maxMetaEntries  = 32
	maxMetaKeyLen   = 64
	maxMetaValueLen = 512
)

// createDeployment handles POST /api/v1/projects/{name}/deployments.
func (s *Server) createDeployment(w http.ResponseWriter, r *http.Request) error {
	p, err := s.project(r)
	if err != nil {
		return err
	}
	// The body is optional: a deployment that carries no metadata is a bare POST,
	// which is what `curl -X POST` and any shell-driven CI job send.
	var req api.CreateDeploymentRequest
	if r.ContentLength != 0 {
		if err := httpx.DecodeJSON(w, r, s.maxJSON(), &req); err != nil {
			return err
		}
	}
	if err := checkMeta(req.Meta); err != nil {
		return err
	}
	id, err := s.identity(r)
	if err != nil {
		return err
	}

	dep, err := s.Deploy.Create(r.Context(), p, id.KeyID, req.Meta)
	if err != nil {
		return err
	}
	httpx.LogAttr(r.Context(), "deployment", dep.PublicID)
	w.Header().Set("Location", api.PathDeployment(p.Name, dep.PublicID))
	httpx.WriteJSON(w, http.StatusCreated, deploymentOf(p, dep))
	return nil
}

// setManifest handles POST .../deployments/{id}/manifest.
//
// The body is walked one entry at a time rather than unmarshalled whole: a
// 50,000-file manifest would otherwise be resident twice over, once as raw JSON
// and once as structs, for no benefit — nothing here needs to see the entries
// together.
func (s *Server) setManifest(w http.ResponseWriter, r *http.Request) error {
	p, dep, err := s.deployment(r)
	if err != nil {
		return err
	}

	r.Body = http.MaxBytesReader(w, r.Body, s.maxManifest())
	var (
		files      []store.FileRow
		paths      = pathutil.NewSet(0)
		unique     = make(map[cas.Digest]struct{})
		totalBytes int64
	)
	err = decodeManifest(json.NewDecoder(r.Body), func(f api.FileEntry) error {
		if err := paths.Add(f.Path); err != nil {
			return api.Errorf(api.CodeInvalidPath, "%s", err)
		}
		digest, err := cas.ParseDigest(f.Digest)
		if err != nil {
			return api.Errorf(api.CodeBadRequest, "%s: %s", f.Path, err)
		}
		if f.Size < 0 {
			return api.Errorf(api.CodeBadRequest, "%s: size must not be negative", f.Path)
		}
		if f.Size > p.MaxFileBytes {
			return api.Errorf(api.CodeLimitExceeded,
				"%s is %d bytes; this project allows at most %d per file", f.Path, f.Size, p.MaxFileBytes)
		}
		if len(files) >= p.MaxFiles {
			return api.Errorf(api.CodeLimitExceeded,
				"a deployment of this project may contain at most %d files", p.MaxFiles)
		}
		totalBytes += f.Size
		if totalBytes > p.MaxTotalBytes {
			return api.Errorf(api.CodeLimitExceeded,
				"a deployment of this project may total at most %d bytes", p.MaxTotalBytes)
		}
		unique[digest] = struct{}{}
		files = append(files, store.FileRow{Path: f.Path, Digest: digest, Size: f.Size})
		return nil
	})
	if err != nil {
		return err
	}
	if len(files) == 0 {
		return api.Errorf(api.CodeBadRequest, "a manifest must list at least one file")
	}

	missing, missingBytes, err := s.Deploy.SetManifest(r.Context(), dep, files)
	if err != nil {
		return err
	}
	out := api.ManifestResponse{
		Missing:      make([]string, 0, len(missing)),
		MissingBytes: missingBytes,
		Have:         len(unique) - len(missing),
		FileCount:    len(files),
		TotalBytes:   totalBytes,
	}
	for _, d := range missing {
		out.Missing = append(out.Missing, d.String())
	}
	httpx.WriteJSON(w, http.StatusOK, out)
	return nil
}

// finalize handles POST .../deployments/{id}/finalize.
func (s *Server) finalize(w http.ResponseWriter, r *http.Request) error {
	p, dep, err := s.deployment(r)
	if err != nil {
		return err
	}
	if err := httpx.NoBody(r); err != nil {
		return err
	}
	dep, err = s.Deploy.Finalize(r.Context(), p, dep)
	if err != nil {
		return err
	}
	httpx.WriteJSON(w, http.StatusOK, deploymentOf(p, dep))
	return nil
}

// activate handles POST .../deployments/{id}/activate.
//
// This is also the rollback endpoint: activating an older ready deployment is
// the same operation, and costs the same single pointer store.
func (s *Server) activate(w http.ResponseWriter, r *http.Request) error {
	p, dep, err := s.deployment(r)
	if err != nil {
		return err
	}
	if err := httpx.NoBody(r); err != nil {
		return err
	}
	dep, err = s.Deploy.Activate(r.Context(), p, dep)
	if err != nil {
		return err
	}
	out := deploymentOf(p, dep)
	if s.BaseURL != "" {
		out.URL = api.SiteURL(s.BaseURL, p.Name)
	}
	httpx.WriteJSON(w, http.StatusOK, out)
	return nil
}

// listDeployments handles GET .../deployments.
func (s *Server) listDeployments(w http.ResponseWriter, r *http.Request) error {
	p, err := s.project(r)
	if err != nil {
		return err
	}
	limit, err := intQuery(r, "limit", 100, 1, 500)
	if err != nil {
		return err
	}
	state, err := parseState(r.URL.Query().Get("state"))
	if err != nil {
		return err
	}
	deps, next, err := s.DB.ListDeployments(r.Context(), p.ID, state, limit, r.URL.Query().Get("cursor"))
	if err != nil {
		return err
	}
	out := api.DeploymentList{Deployments: make([]api.Deployment, 0, len(deps)), NextCursor: next}
	for _, dep := range deps {
		out.Deployments = append(out.Deployments, deploymentOf(p, dep))
	}
	httpx.WriteJSON(w, http.StatusOK, out)
	return nil
}

// getDeployment handles GET .../deployments/{id}, with ?files=true adding the
// manifest.
//
// The manifest is opt-in because it can be fifty thousand entries: a listing
// that carried it by default would make `pages deployment list` unusable on a
// large site for information nobody asked for.
func (s *Server) getDeployment(w http.ResponseWriter, r *http.Request) error {
	p, dep, err := s.deployment(r)
	if err != nil {
		return err
	}
	out := deploymentOf(p, dep)
	if r.URL.Query().Get("files") == "true" {
		files, err := s.DB.DeploymentFiles(r.Context(), dep.ID)
		if err != nil {
			return err
		}
		out.Files = make([]api.FileEntry, 0, len(files))
		for _, f := range files {
			out.Files = append(out.Files, api.FileEntry{
				Path: f.Path, Digest: f.Digest.String(), Size: f.Size,
			})
		}
	}
	if dep.Active && s.BaseURL != "" {
		out.URL = api.SiteURL(s.BaseURL, p.Name)
	}
	httpx.WriteJSON(w, http.StatusOK, out)
	return nil
}

// deleteDeployment handles DELETE .../deployments/{id}. Deleting the active one
// is a 409: the client is expected to activate something else first, so that
// the project is never left with nothing to serve by accident.
func (s *Server) deleteDeployment(w http.ResponseWriter, r *http.Request) error {
	if err := httpx.NoBody(r); err != nil {
		return err
	}
	p, dep, err := s.deployment(r)
	if err != nil {
		return err
	}
	if err := s.Deploy.Delete(r.Context(), p, dep); err != nil {
		return err
	}
	w.WriteHeader(http.StatusNoContent)
	return nil
}

// parseState validates the ?state= filter. The empty string means no filter;
// anything else must be a state that exists, so a typo is a 400 rather than a
// silently empty list.
func parseState(raw string) (store.State, error) {
	switch raw {
	case "":
		return "", nil
	case api.StatePending, api.StateUploading, api.StateReady, api.StateFailed, api.StateDeleting:
		return store.State(raw), nil
	}
	return "", api.Errorf(api.CodeBadRequest, "unknown deployment state %q", raw)
}

// deployment resolves both the {name} and {id} wildcards.
//
// The deployment is looked up within the project, never on its own: a
// project-scoped caller that guessed another project's deployment id gets the
// same "no such deployment" as one that guessed a nonexistent one.
func (s *Server) deployment(r *http.Request) (*store.Project, *store.Deployment, error) {
	p, err := s.project(r)
	if err != nil {
		return nil, nil, err
	}
	dep, err := s.DB.DeploymentByPublicID(r.Context(), p.ID, r.PathValue("id"))
	if err != nil {
		if errors.Is(err, store.ErrNotFound) {
			return nil, nil, api.Errorf(api.CodeNotFound, "no such deployment")
		}
		return nil, nil, err
	}
	httpx.LogAttr(r.Context(), "deployment", dep.PublicID)
	return p, dep, nil
}

// decodeManifest streams {"files":[...]} and calls onFile for each entry.
func decodeManifest(dec *json.Decoder, onFile func(api.FileEntry) error) error {
	if err := expectDelim(dec, '{', "manifest must be a JSON object"); err != nil {
		return err
	}
	seen := false
	for dec.More() {
		tok, err := dec.Token()
		if err != nil {
			return badJSON(err)
		}
		key, _ := tok.(string)
		if key != "files" {
			// Unknown keys are skipped rather than rejected: a newer CLI may send
			// a field this server predates, and the body is bounded anyway.
			var skip json.RawMessage
			if err := dec.Decode(&skip); err != nil {
				return badJSON(err)
			}
			continue
		}
		seen = true
		if err := expectDelim(dec, '[', "files must be an array"); err != nil {
			return err
		}
		for dec.More() {
			var f api.FileEntry
			if err := dec.Decode(&f); err != nil {
				return badJSON(err)
			}
			if err := onFile(f); err != nil {
				return err
			}
		}
		if _, err := dec.Token(); err != nil { // closing ]
			return badJSON(err)
		}
	}
	if _, err := dec.Token(); err != nil { // closing }
		return badJSON(err)
	}
	if !seen {
		return api.Errorf(api.CodeBadRequest, "manifest is missing the files array")
	}
	return nil
}

func expectDelim(dec *json.Decoder, want json.Delim, msg string) error {
	tok, err := dec.Token()
	if err != nil {
		return badJSON(err)
	}
	if d, ok := tok.(json.Delim); !ok || d != want {
		return api.Errorf(api.CodeBadRequest, "%s", msg)
	}
	return nil
}

// badJSON turns a decoder failure into a client error, keeping the body-size
// rejection distinguishable from a syntax one.
func badJSON(err error) error {
	var maxErr *http.MaxBytesError
	if errors.As(err, &maxErr) {
		return api.Errorf(api.CodePayloadTooLarge, "manifest exceeds %d bytes", maxErr.Limit)
	}
	var syn *json.SyntaxError
	if errors.As(err, &syn) {
		return api.Errorf(api.CodeBadRequest, "malformed JSON at byte %d", syn.Offset)
	}
	var typeErr *json.UnmarshalTypeError
	if errors.As(err, &typeErr) {
		return api.Errorf(api.CodeBadRequest, "field %q: want %s", typeErr.Field, typeErr.Type)
	}
	return api.Errorf(api.CodeBadRequest, "malformed manifest")
}

func checkMeta(meta map[string]string) error {
	if len(meta) > maxMetaEntries {
		return api.Errorf(api.CodeBadRequest, "meta may hold at most %d entries", maxMetaEntries)
	}
	for k, v := range meta {
		if k == "" {
			return api.Errorf(api.CodeBadRequest, "meta keys must not be empty")
		}
		if err := checkText("meta key", k, maxMetaKeyLen); err != nil {
			return err
		}
		if err := checkText("meta value of "+k, v, maxMetaValueLen); err != nil {
			return err
		}
	}
	return nil
}

func (s *Server) maxManifest() int64 {
	if s.Limits.MaxManifestBytes > 0 {
		return s.Limits.MaxManifestBytes
	}
	return 64 << 20
}