package ui

import (
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"git.wntrmute.dev/kyle/mcias/internal/auth"
	"git.wntrmute.dev/kyle/mcias/internal/crypto"
	"git.wntrmute.dev/kyle/mcias/internal/db"
	"git.wntrmute.dev/kyle/mcias/internal/model"
	"git.wntrmute.dev/kyle/mcias/internal/validate"
)

// knownRoles lists the built-in roles shown as checkboxes in the roles editor.
var knownRoles = []string{"admin", "user", "service"}

// handleAccountsList renders the accounts list page.
func (u *UIServer) handleAccountsList(w http.ResponseWriter, r *http.Request) {
	csrfToken, err := u.setCSRFCookies(w)
	if err != nil {
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}

	accounts, err := u.db.ListAccounts()
	if err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "failed to load accounts")
		return
	}

	u.render(w, "accounts", AccountsData{
		PageData: PageData{CSRFToken: csrfToken},
		Accounts: accounts,
	})
}

// handleCreateAccount creates a new account and returns the account_row fragment.
func (u *UIServer) handleCreateAccount(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxFormBytes)
	if err := r.ParseForm(); err != nil {
		u.renderError(w, r, http.StatusBadRequest, "invalid form")
		return
	}

	username := strings.TrimSpace(r.FormValue("username"))
	password := r.FormValue("password")
	accountTypeStr := r.FormValue("account_type")

	// Security (F-12): validate username length and character set.
	if err := validate.Username(username); err != nil {
		u.renderError(w, r, http.StatusBadRequest, err.Error())
		return
	}

	accountType := model.AccountTypeHuman
	if accountTypeStr == string(model.AccountTypeSystem) {
		accountType = model.AccountTypeSystem
	}

	var passwordHash string
	if password != "" {
		// Security (F-13): enforce minimum length before hashing.
		if err := validate.Password(password); err != nil {
			u.renderError(w, r, http.StatusBadRequest, err.Error())
			return
		}
		argonCfg := auth.ArgonParams{
			Time:    u.cfg.Argon2.Time,
			Memory:  u.cfg.Argon2.Memory,
			Threads: u.cfg.Argon2.Threads,
		}
		var err error
		passwordHash, err = auth.HashPassword(password, argonCfg)
		if err != nil {
			u.logger.Error("hash password", "error", err)
			u.renderError(w, r, http.StatusInternalServerError, "internal error")
			return
		}
	} else if accountType == model.AccountTypeHuman {
		u.renderError(w, r, http.StatusBadRequest, "password is required for human accounts")
		return
	}

	claims := claimsFromContext(r.Context())
	var actorID *int64
	if claims != nil {
		acct, err := u.db.GetAccountByUUID(claims.Subject)
		if err == nil {
			actorID = &acct.ID
		}
	}

	acct, err := u.db.CreateAccount(username, accountType, passwordHash)
	if err != nil {
		u.renderError(w, r, http.StatusInternalServerError, fmt.Sprintf("create account: %v", err))
		return
	}

	u.writeAudit(r, model.EventAccountCreated, actorID, &acct.ID,
		fmt.Sprintf(`{"username":%q,"type":%q}`, username, accountType))

	u.render(w, "account_row", acct)
}

// handleAccountDetail renders the account detail page.
func (u *UIServer) handleAccountDetail(w http.ResponseWriter, r *http.Request) {
	csrfToken, err := u.setCSRFCookies(w)
	if err != nil {
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}

	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}

	roles, err := u.db.GetRoles(acct.ID)
	if err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "failed to load roles")
		return
	}

	tokens, err := u.db.ListTokensForAccount(acct.ID)
	if err != nil {
		u.logger.Warn("list tokens for account", "error", err)
		tokens = nil
	}

	// Load PG credentials for system accounts only; leave nil for human accounts
	// and when no credentials have been stored yet.
	var pgCred *model.PGCredential
	if acct.AccountType == model.AccountTypeSystem {
		pgCred, err = u.db.ReadPGCredentials(acct.ID)
		if err != nil && !errors.Is(err, db.ErrNotFound) {
			u.logger.Warn("read pg credentials", "error", err)
		}
		// ErrNotFound is expected when no credentials have been stored yet.
	}

	tags, err := u.db.GetAccountTags(acct.ID)
	if err != nil {
		u.logger.Warn("get account tags", "error", err)
		tags = nil
	}

	u.render(w, "account_detail", AccountDetailData{
		PageData: PageData{CSRFToken: csrfToken},
		Account:  acct,
		Roles:    roles,
		AllRoles: knownRoles,
		Tokens:   tokens,
		PGCred:   pgCred,
		Tags:     tags,
	})
}

// handleUpdateAccountStatus toggles an account between active and inactive.
func (u *UIServer) handleUpdateAccountStatus(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxFormBytes)
	if err := r.ParseForm(); err != nil {
		u.renderError(w, r, http.StatusBadRequest, "invalid form")
		return
	}

	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}

	statusStr := r.FormValue("status")
	var newStatus model.AccountStatus
	switch statusStr {
	case string(model.AccountStatusActive):
		newStatus = model.AccountStatusActive
	case string(model.AccountStatusInactive):
		newStatus = model.AccountStatusInactive
	default:
		u.renderError(w, r, http.StatusBadRequest, "invalid status")
		return
	}

	if err := u.db.UpdateAccountStatus(acct.ID, newStatus); err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "update failed")
		return
	}
	acct.Status = newStatus

	claims := claimsFromContext(r.Context())
	var actorID *int64
	if claims != nil {
		actor, err := u.db.GetAccountByUUID(claims.Subject)
		if err == nil {
			actorID = &actor.ID
		}
	}
	u.writeAudit(r, model.EventAccountUpdated, actorID, &acct.ID,
		fmt.Sprintf(`{"status":%q}`, newStatus))

	// Respond with the updated row (for HTMX outerHTML swap on accounts list)
	// or updated status cell (for HTMX innerHTML swap on account detail).
	// The hx-target in accounts.html targets the whole <tr>; in account_detail.html
	// it targets #status-cell. We detect which by checking the request path context.
	if strings.Contains(r.Header.Get("HX-Target"), "status-cell") || r.Header.Get("HX-Target") == "status-cell" {
		data := AccountDetailData{
			PageData: PageData{CSRFToken: ""},
			Account:  acct,
		}
		u.render(w, "account_status", data)
	} else {
		u.render(w, "account_row", acct)
	}
}

// handleDeleteAccount soft-deletes an account and returns empty body (HTMX removes row).
func (u *UIServer) handleDeleteAccount(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}

	if err := u.db.UpdateAccountStatus(acct.ID, model.AccountStatusDeleted); err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "delete failed")
		return
	}

	// Revoke all active tokens for the deleted account.
	if err := u.db.RevokeAllUserTokens(acct.ID, "account_deleted"); err != nil {
		u.logger.Warn("revoke tokens for deleted account", "account_id", acct.ID, "error", err)
	}

	claims := claimsFromContext(r.Context())
	var actorID *int64
	if claims != nil {
		actor, err := u.db.GetAccountByUUID(claims.Subject)
		if err == nil {
			actorID = &actor.ID
		}
	}
	u.writeAudit(r, model.EventAccountDeleted, actorID, &acct.ID, "")

	// Return empty body; HTMX will remove the row via hx-swap="outerHTML".
	w.WriteHeader(http.StatusOK)
}

// handleRolesEditForm returns the roles editor fragment (GET — no CSRF check needed).
func (u *UIServer) handleRolesEditForm(w http.ResponseWriter, r *http.Request) {
	csrfToken, err := u.setCSRFCookies(w)
	if err != nil {
		http.Error(w, "internal error", http.StatusInternalServerError)
		return
	}

	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}

	roles, err := u.db.GetRoles(acct.ID)
	if err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "failed to load roles")
		return
	}

	u.render(w, "roles_editor", AccountDetailData{
		PageData: PageData{CSRFToken: csrfToken},
		Account:  acct,
		Roles:    roles,
		AllRoles: knownRoles,
	})
}

// handleSetRoles replaces the full role set for an account.
func (u *UIServer) handleSetRoles(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxFormBytes)
	if err := r.ParseForm(); err != nil {
		u.renderError(w, r, http.StatusBadRequest, "invalid form")
		return
	}

	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}

	// Collect checked roles + optional custom role.
	roles := r.Form["roles"] // multi-value from checkboxes
	if custom := strings.TrimSpace(r.FormValue("custom_role")); custom != "" {
		roles = append(roles, custom)
	}

	claims := claimsFromContext(r.Context())
	var actorID *int64
	if claims != nil {
		actor, err := u.db.GetAccountByUUID(claims.Subject)
		if err == nil {
			actorID = &actor.ID
		}
	}

	if err := u.db.SetRoles(acct.ID, roles, actorID); err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "failed to set roles")
		return
	}

	u.writeAudit(r, model.EventRoleGranted, actorID, &acct.ID,
		fmt.Sprintf(`{"roles":%q}`, strings.Join(roles, ",")))

	csrfToken, err := u.setCSRFCookies(w)
	if err != nil {
		csrfToken = ""
	}

	u.render(w, "roles_editor", AccountDetailData{
		PageData: PageData{CSRFToken: csrfToken},
		Account:  acct,
		Roles:    roles,
		AllRoles: knownRoles,
	})
}

// handleRevokeToken revokes a specific token by JTI.
func (u *UIServer) handleRevokeToken(w http.ResponseWriter, r *http.Request) {
	jti := r.PathValue("jti")
	if jti == "" {
		u.renderError(w, r, http.StatusBadRequest, "missing JTI")
		return
	}

	if err := u.db.RevokeToken(jti, "ui_revoke"); err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "revoke failed")
		return
	}

	claims := claimsFromContext(r.Context())
	var actorID *int64
	if claims != nil {
		actor, err := u.db.GetAccountByUUID(claims.Subject)
		if err == nil {
			actorID = &actor.ID
		}
	}
	u.writeAudit(r, model.EventTokenRevoked, actorID, nil,
		fmt.Sprintf(`{"jti":%q,"reason":"ui_revoke"}`, jti))

	// Return empty body; HTMX removes the row.
	w.WriteHeader(http.StatusOK)
}

// handleSetPGCreds stores (or replaces) encrypted Postgres credentials for a
// system account. The submitted password is encrypted with AES-256-GCM using the
// server master key before storage and is never echoed back in the response.
//
// Security: Only system accounts may hold PG credentials. The password field is
// write-only — the UI displays only connection metadata (host, port, database,
// username) after save. Audit event EventPGCredUpdated is recorded on success.
func (u *UIServer) handleSetPGCreds(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxFormBytes)
	if err := r.ParseForm(); err != nil {
		u.renderError(w, r, http.StatusBadRequest, "invalid form")
		return
	}

	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}

	// Security: PG credentials are only meaningful for system accounts.
	if acct.AccountType != model.AccountTypeSystem {
		u.renderError(w, r, http.StatusBadRequest, "postgres credentials are only available for system accounts")
		return
	}

	host := strings.TrimSpace(r.FormValue("host"))
	portStr := strings.TrimSpace(r.FormValue("port"))
	dbName := strings.TrimSpace(r.FormValue("database"))
	username := strings.TrimSpace(r.FormValue("username"))
	password := r.FormValue("password")

	if host == "" {
		u.renderError(w, r, http.StatusBadRequest, "host is required")
		return
	}
	if dbName == "" {
		u.renderError(w, r, http.StatusBadRequest, "database is required")
		return
	}
	if username == "" {
		u.renderError(w, r, http.StatusBadRequest, "username is required")
		return
	}
	// Security: password is required on every write — the UI does not carry the
	// existing password, so callers must supply it explicitly.
	if password == "" {
		u.renderError(w, r, http.StatusBadRequest, "password is required")
		return
	}

	port := 5432
	if portStr != "" {
		port, err = strconv.Atoi(portStr)
		if err != nil || port < 1 || port > 65535 {
			u.renderError(w, r, http.StatusBadRequest, "port must be an integer between 1 and 65535")
			return
		}
	}

	// Security: encrypt the password with AES-256-GCM before storage.
	// A fresh random nonce is generated per call by SealAESGCM; nonce reuse
	// is not possible. The plaintext password is not retained after this call.
	enc, nonce, err := crypto.SealAESGCM(u.masterKey, []byte(password))
	if err != nil {
		u.logger.Error("encrypt pg password", "error", err)
		u.renderError(w, r, http.StatusInternalServerError, "internal error")
		return
	}

	if err := u.db.WritePGCredentials(acct.ID, host, port, dbName, username, enc, nonce); err != nil {
		u.logger.Error("write pg credentials", "error", err)
		u.renderError(w, r, http.StatusInternalServerError, "failed to save credentials")
		return
	}

	claims := claimsFromContext(r.Context())
	var actorID *int64
	if claims != nil {
		actor, err := u.db.GetAccountByUUID(claims.Subject)
		if err == nil {
			actorID = &actor.ID
		}
	}
	u.writeAudit(r, model.EventPGCredUpdated, actorID, &acct.ID, "")

	// Re-read the stored record to populate the metadata display.
	// The encrypted blobs are loaded but the password field (PGPassword) remains
	// empty — it is only decrypted on explicit admin retrieval via gRPC.
	pgCred, err := u.db.ReadPGCredentials(acct.ID)
	if err != nil {
		u.logger.Warn("re-read pg credentials after write", "error", err)
		pgCred = nil
	}

	csrfToken, err := u.setCSRFCookies(w)
	if err != nil {
		csrfToken = ""
	}

	u.render(w, "pgcreds_form", AccountDetailData{
		PageData: PageData{CSRFToken: csrfToken},
		Account:  acct,
		PGCred:   pgCred,
	})
}

// handleIssueSystemToken issues a long-lived service token for a system account.
func (u *UIServer) handleIssueSystemToken(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	acct, err := u.db.GetAccountByUUID(id)
	if err != nil {
		u.renderError(w, r, http.StatusNotFound, "account not found")
		return
	}
	if acct.AccountType != model.AccountTypeSystem {
		u.renderError(w, r, http.StatusBadRequest, "only system accounts can have service tokens")
		return
	}

	roles, err := u.db.GetRoles(acct.ID)
	if err != nil {
		u.renderError(w, r, http.StatusInternalServerError, "failed to load roles")
		return
	}

	// Security: revoke the previous system token before issuing a new one (F-16).
	// This matches the pattern in the REST handleTokenIssue and gRPC IssueServiceToken
	// so that old tokens do not remain valid after rotation.
	existing, err := u.db.GetSystemToken(acct.ID)
	if err == nil {
		_ = u.db.RevokeToken(existing.JTI, "rotated")
	}

	expiry := u.cfg.ServiceExpiry()
	tokenStr, claims, err := u.issueToken(acct.UUID, roles, expiry)
	if err != nil {
		u.logger.Error("issue system token", "error", err)
		u.renderError(w, r, http.StatusInternalServerError, "failed to issue token")
		return
	}

	if err := u.db.TrackToken(claims.JTI, acct.ID, claims.IssuedAt, claims.ExpiresAt); err != nil {
		u.logger.Error("track system token", "error", err)
		u.renderError(w, r, http.StatusInternalServerError, "failed to track token")
		return
	}

	// Store as system token for easy retrieval.
	if err := u.db.SetSystemToken(acct.ID, claims.JTI, claims.ExpiresAt); err != nil {
		u.logger.Warn("set system token record", "error", err)
	}

	actorClaims := claimsFromContext(r.Context())
	var actorID *int64
	if actorClaims != nil {
		actor, err := u.db.GetAccountByUUID(actorClaims.Subject)
		if err == nil {
			actorID = &actor.ID
		}
	}
	u.writeAudit(r, model.EventTokenIssued, actorID, &acct.ID,
		fmt.Sprintf(`{"jti":%q,"via":"ui_system_token"}`, claims.JTI))

	// Re-fetch token list including the new token.
	tokens, err := u.db.ListTokensForAccount(acct.ID)
	if err != nil {
		u.logger.Warn("list tokens after issue", "error", err)
		tokens = nil
	}

	csrfToken, err := u.setCSRFCookies(w)
	if err != nil {
		csrfToken = ""
	}

	// Flash the raw token once at the top so the operator can copy it.
	u.render(w, "token_list", AccountDetailData{
		PageData: PageData{
			CSRFToken: csrfToken,
			Flash:     fmt.Sprintf("Token issued. Copy now — it will not be shown again: %s", tokenStr),
		},
		Account: acct,
		Tokens:  tokens,
	})
}