package main

import (
	"context"
	"encoding/json"
	"fmt"
	"git.cin.su/m/Assistant/adapters/postgres"
	"git.cin.su/m/Assistant/contracts/capability"
	"git.cin.su/m/Assistant/contracts/identity"
	"git.cin.su/m/Assistant/contracts/situation"
	"git.cin.su/m/Assistant/contracts/work"
	capabilitydomain "git.cin.su/m/Assistant/modules/capability/domain"
	identitydomain "git.cin.su/m/Assistant/modules/identity/domain"
	situationdomain "git.cin.su/m/Assistant/modules/situation/domain"
	"git.cin.su/m/Assistant/runtime/health"
	"io"
	"log"
	"net/http"
	"os"
	"strconv"
	"strings"
	"time"
)

const maxCreatorCredentialsBytes = 4 << 10

func main() {
	addr := os.Getenv("LISTEN_ADDR")
	if addr == "" {
		addr = ":8080"
	}
	bootstrapToken, err := readRequiredSecret("CREATOR_BOOTSTRAP_TOKEN")
	if err != nil {
		log.Fatal(err)
	}
	sessionKeyValue, err := readRequiredSecret("CREATOR_SESSION_SIGNING_KEY")
	if err != nil {
		log.Fatal(err)
	}
	creatorPassword, err := readRequiredSecret("CREATOR_PASSWORD")
	if err != nil {
		log.Fatal(err)
	}
	sessionKey := []byte(sessionKeyValue)
	creatorUsername := os.Getenv("CREATOR_USERNAME")
	repository, err := postgres.OpenSituation(context.Background(), postgres.ContinuityConfig{Host: os.Getenv("POSTGRES_HOST"), Port: os.Getenv("POSTGRES_PORT"), Database: os.Getenv("POSTGRES_DATABASE"), User: os.Getenv("POSTGRES_USER"), Password: os.Getenv("POSTGRES_PASSWORD")})
	if err != nil {
		log.Fatal(err)
	}
	defer repository.Close()
	workRepository, err := postgres.OpenWork(context.Background(), postgres.ContinuityConfig{Host: os.Getenv("POSTGRES_HOST"), Port: os.Getenv("POSTGRES_PORT"), Database: os.Getenv("POSTGRES_DATABASE"), User: os.Getenv("WORK_POSTGRES_USER"), Password: os.Getenv("WORK_POSTGRES_PASSWORD")})
	if err != nil {
		log.Fatal(err)
	}
	defer workRepository.Close()
	capabilityRepository, err := postgres.OpenCapability(context.Background(), postgres.ContinuityConfig{Host: os.Getenv("POSTGRES_HOST"), Port: os.Getenv("POSTGRES_PORT"), Database: os.Getenv("POSTGRES_DATABASE"), User: os.Getenv("CAPABILITY_POSTGRES_USER"), Password: os.Getenv("CAPABILITY_POSTGRES_PASSWORD")})
	if err != nil {
		log.Fatal(err)
	}
	defer capabilityRepository.Close()
	identityRepository, err := postgres.OpenIdentity(context.Background(), postgres.ContinuityConfig{Host: os.Getenv("POSTGRES_HOST"), Port: os.Getenv("POSTGRES_PORT"), Database: os.Getenv("POSTGRES_DATABASE"), User: os.Getenv("IDENTITY_POSTGRES_USER"), Password: os.Getenv("IDENTITY_POSTGRES_PASSWORD")})
	if err != nil {
		log.Fatal(err)
	}
	defer identityRepository.Close()
	mux := http.NewServeMux()
	authenticateCreator := func(w http.ResponseWriter, r *http.Request) (identity.CreatorSession, bool) {
		session, err := identitydomain.ValidateCreatorSession(sessionKey, bearerToken(r), time.Now())
		if err != nil {
			http.Error(w, "creator session denied", http.StatusUnauthorized)
			return identity.CreatorSession{}, false
		}
		return session, true
	}
	resolveFocus := func(r *http.Request) (situation.FocusBinding, error) {
		runtime := situation.RuntimeBinding{SessionID: situation.SessionID(r.URL.Query().Get("session_id")), Workspace: situation.WorkspaceID(r.URL.Query().Get("workspace_id"))}
		bindings, err := repository.ByRuntime(r.Context(), runtime)
		if err != nil {
			return situation.FocusBinding{}, err
		}
		return situationdomain.NewResolver(bindings).Resolve(runtime)
	}
	mux.Handle("/healthz", health.Handler{Runtime: "core-runtime", SemanticGeneration: 1, ArchitectureGeneration: 1})
	mux.HandleFunc("POST /v1/creator/sessions", creatorSessionHandler(bootstrapToken, creatorUsername, creatorPassword, sessionKey, time.Now))
	mux.HandleFunc("GET /v1/creator/sessions/current", func(w http.ResponseWriter, r *http.Request) {
		session, ok := authenticateCreator(w, r)
		if !ok {
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(session)
	})
	mux.HandleFunc("GET /v1/creator/focus", func(w http.ResponseWriter, r *http.Request) {
		session, ok := authenticateCreator(w, r)
		if !ok {
			return
		}
		focus, err := resolveFocus(r)
		if err != nil {
			http.Error(w, "creator focus unavailable", http.StatusConflict)
			return
		}
		if focus.ActorID != session.ActorID {
			http.Error(w, "creator focus denied", http.StatusForbidden)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(focus)
	})
	mux.HandleFunc("GET /v1/creator/tasks/{id}", func(w http.ResponseWriter, r *http.Request) {
		session, ok := authenticateCreator(w, r)
		if !ok {
			return
		}
		focus, err := resolveFocus(r)
		if err != nil || focus.ActorID != session.ActorID {
			http.Error(w, "creator focus denied", http.StatusForbidden)
			return
		}
		target, err := workRepository.Load(r.Context(), work.TaskID(r.PathValue("id")))
		if err != nil {
			http.Error(w, "task not found", http.StatusNotFound)
			return
		}
		if err := situationdomain.ValidateTaskTarget(focus, target); err != nil {
			http.Error(w, "task outside creator focus", http.StatusForbidden)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(target)
	})
	mux.HandleFunc("GET /v1/creator/capabilities/{id}/health", func(w http.ResponseWriter, r *http.Request) {
		if _, ok := authenticateCreator(w, r); !ok {
			return
		}
		status, err := capabilityRepository.LoadHealth(r.Context(), capability.CapabilityID(r.PathValue("id")))
		if err != nil {
			http.Error(w, "capability health not found", http.StatusNotFound)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(status)
	})
	mux.HandleFunc("GET /v1/principal-bindings/{actor}/{principal}", func(w http.ResponseWriter, r *http.Request) {
		binding, err := identityRepository.LoadBinding(r.Context(), identity.ActorID(r.PathValue("actor")), identity.PrincipalID(r.PathValue("principal")))
		if err != nil {
			http.Error(w, "principal binding not found", http.StatusNotFound)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(binding)
	})
	mux.HandleFunc("GET /v1/tasks/{id}", func(w http.ResponseWriter, r *http.Request) {
		target, err := workRepository.Load(r.Context(), work.TaskID(r.PathValue("id")))
		if err != nil {
			http.Error(w, "task not found", http.StatusNotFound)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(target)
	})
	mux.HandleFunc("POST /v1/capabilities/health", func(w http.ResponseWriter, r *http.Request) {
		var status capability.Health
		if err := json.NewDecoder(r.Body).Decode(&status); err != nil {
			http.Error(w, "invalid capability health", http.StatusBadRequest)
			return
		}
		if err := capabilitydomain.ValidateHealth(status); err != nil {
			http.Error(w, "invalid capability health", http.StatusBadRequest)
			return
		}
		if err := capabilityRepository.SaveHealth(r.Context(), status); err != nil {
			http.Error(w, "save capability health", http.StatusInternalServerError)
			return
		}
		w.WriteHeader(http.StatusCreated)
	})
	mux.HandleFunc("GET /v1/capabilities/{id}/health", func(w http.ResponseWriter, r *http.Request) {
		status, err := capabilityRepository.LoadHealth(r.Context(), capability.CapabilityID(r.PathValue("id")))
		if err != nil {
			http.Error(w, "capability health not found", http.StatusNotFound)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(status)
	})
	mux.HandleFunc("GET /v1/capability-bindings/{id}/revisions/{revision}", func(w http.ResponseWriter, r *http.Request) {
		revision, err := strconv.ParseInt(r.PathValue("revision"), 10, 64)
		if err != nil || revision < 1 {
			http.Error(w, "invalid binding revision", http.StatusBadRequest)
			return
		}
		binding, err := capabilityRepository.LoadBinding(r.Context(), capability.CapabilityBindingID(r.PathValue("id")), revision)
		if err != nil {
			http.Error(w, "capability binding not found", http.StatusNotFound)
			return
		}
		if err = capabilitydomain.ValidateBinding(binding); err != nil {
			http.Error(w, "capability binding invalid", http.StatusConflict)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(binding)
	})
	mux.HandleFunc("GET /v1/capability-bindings/active", func(w http.ResponseWriter, r *http.Request) {
		capabilityID := capability.CapabilityID(r.URL.Query().Get("capability_id"))
		ownerID := identity.PrincipalID(r.URL.Query().Get("owner_principal_id"))
		if capabilityID == "" || ownerID == "" {
			http.Error(w, "invalid binding query", http.StatusBadRequest)
			return
		}
		binding, err := capabilityRepository.LoadActiveBinding(r.Context(), capabilityID, ownerID)
		if err != nil {
			http.Error(w, "active capability binding not found", http.StatusNotFound)
			return
		}
		if err = capabilitydomain.UsableBinding(binding); err != nil {
			http.Error(w, "active capability binding unavailable", http.StatusConflict)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(binding)
	})
	mux.HandleFunc("POST /v1/capabilities/health-projection/rebuild", func(w http.ResponseWriter, r *http.Request) {
		rebuilt, err := capabilityRepository.RebuildHealthProjection(r.Context())
		if err != nil {
			http.Error(w, "rebuild capability health projection", http.StatusInternalServerError)
			return
		}
		_ = json.NewEncoder(w).Encode(struct{ Rebuilt int64 }{rebuilt})
	})
	mux.HandleFunc("POST /v1/focus-bindings", func(w http.ResponseWriter, r *http.Request) {
		var binding situation.FocusBinding
		if err := json.NewDecoder(r.Body).Decode(&binding); err != nil {
			http.Error(w, "invalid focus binding", http.StatusBadRequest)
			return
		}
		if err := repository.Save(r.Context(), binding); err != nil {
			http.Error(w, "save focus binding", http.StatusInternalServerError)
			return
		}
		w.WriteHeader(http.StatusCreated)
	})
	mux.HandleFunc("GET /v1/focus", func(w http.ResponseWriter, r *http.Request) {
		focus, err := resolveFocus(r)
		if err != nil {
			http.Error(w, err.Error(), http.StatusConflict)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(focus)
	})
	mux.HandleFunc("POST /v1/tasks", func(w http.ResponseWriter, r *http.Request) {
		var target work.TaskTarget
		if err := json.NewDecoder(r.Body).Decode(&target); err != nil {
			http.Error(w, "invalid task", 400)
			return
		}
		if err := workRepository.Create(r.Context(), target); err != nil {
			http.Error(w, "create task", 500)
			return
		}
		w.WriteHeader(http.StatusCreated)
	})
	mux.HandleFunc("POST /v1/tasks/{id}/commit", func(w http.ResponseWriter, r *http.Request) {
		var target work.TaskTarget
		if err := json.NewDecoder(r.Body).Decode(&target); err != nil {
			http.Error(w, "invalid task commit", 400)
			return
		}
		target.TaskID = work.TaskID(r.PathValue("id"))
		revision, err := workRepository.Commit(r.Context(), target)
		if err != nil {
			http.Error(w, "task revision conflict", http.StatusConflict)
			return
		}
		_ = json.NewEncoder(w).Encode(struct{ Revision work.TaskRevision }{revision})
	})
	mux.HandleFunc("POST /v1/focus-task-commits", func(w http.ResponseWriter, r *http.Request) {
		var request struct {
			SessionID situation.SessionID
			Workspace situation.WorkspaceID
			Target    work.TaskTarget
		}
		if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
			http.Error(w, "invalid guarded commit", http.StatusBadRequest)
			return
		}
		bindings, err := repository.ByRuntime(r.Context(), situation.RuntimeBinding{SessionID: request.SessionID, Workspace: request.Workspace})
		if err != nil {
			http.Error(w, "load focus", http.StatusInternalServerError)
			return
		}
		focus, err := situationdomain.NewResolver(bindings).Resolve(situation.RuntimeBinding{SessionID: request.SessionID, Workspace: request.Workspace})
		if err != nil {
			http.Error(w, "focus unavailable", http.StatusConflict)
			return
		}
		if err := situationdomain.ValidateTaskTarget(focus, request.Target); err != nil {
			http.Error(w, "target outside resolved focus", http.StatusConflict)
			return
		}
		revision, err := workRepository.Commit(r.Context(), request.Target)
		if err != nil {
			http.Error(w, "task revision conflict", http.StatusConflict)
			return
		}
		_ = json.NewEncoder(w).Encode(struct{ Revision work.TaskRevision }{revision})
	})
	log.Printf("core-runtime listening on %s", addr)
	if err := http.ListenAndServe(addr, mux); err != nil {
		log.Fatal(err)
	}
}

func creatorSessionHandler(bootstrapToken, creatorUsername, creatorPassword string, sessionKey []byte, now func() time.Time) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		authenticated := identitydomain.BootstrapMatches(bootstrapToken, bearerToken(r))
		if !authenticated {
			var credentials identity.CreatorCredentials
			decoder := json.NewDecoder(io.LimitReader(r.Body, maxCreatorCredentialsBytes+1))
			decoder.DisallowUnknownFields()
			if err := decoder.Decode(&credentials); err != nil || decoder.Decode(&struct{}{}) != io.EOF {
				http.Error(w, "creator authentication denied", http.StatusUnauthorized)
				return
			}
			authenticated = identitydomain.CreatorCredentialsMatch(creatorUsername, creatorPassword, credentials)
		}
		if !authenticated {
			http.Error(w, "creator authentication denied", http.StatusUnauthorized)
			return
		}
		token, session, err := identitydomain.IssueCreatorSession(sessionKey, now(), 8*time.Hour)
		if err != nil {
			http.Error(w, "creator session unavailable", http.StatusServiceUnavailable)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(struct {
			Token   string
			Session identity.CreatorSession
		}{token, session})
	}
}

func bearerToken(r *http.Request) string {
	value := r.Header.Get("Authorization")
	if !strings.HasPrefix(value, "Bearer ") {
		return ""
	}
	return strings.TrimPrefix(value, "Bearer ")
}

func readRequiredSecret(name string) (string, error) {
	direct, directSet := os.LookupEnv(name)
	fileName, fileSet := os.LookupEnv(name + "_FILE")
	if directSet && fileSet {
		return "", fmt.Errorf("%s and %s_FILE cannot both be configured", name, name)
	}
	if fileSet {
		if fileName == "" {
			return "", fmt.Errorf("%s_FILE is empty", name)
		}
		contents, err := os.ReadFile(fileName)
		if err != nil {
			return "", fmt.Errorf("read %s_FILE: %w", name, err)
		}
		direct = strings.TrimRight(string(contents), "\r\n")
		if strings.ContainsAny(direct, "\r\n") {
			return "", fmt.Errorf("%s_FILE must contain one line", name)
		}
	}
	if direct == "" {
		return "", fmt.Errorf("%s is required", name)
	}
	return direct, nil
}