package api

import (
	"context"
	"errors"
	"strings"

	"github.com/danielgtaylor/huma/v2"
	"github.com/jackc/pgx/v5"

	"completed/internal/auth"
	"completed/internal/db"
)

// sessionCookieName is also used by the auth routes when setting/clearing
// the cookie, so it lives here as the one shared constant.
const sessionCookieName = "session"

// bearerToken extracts the token from "Authorization: Bearer <token>", or
// the empty string if the header is missing or malformed.
func bearerToken(header string) string {
	const prefix = "Bearer "
	if !strings.HasPrefix(header, prefix) {
		return ""
	}
	return strings.TrimPrefix(header, prefix)
}

// tokenFromRequest looks for a session token in the Authorization header
// first (used by the TUI and Fyne clients), falling back to the session
// cookie (used by the web client).
func tokenFromRequest(ctx huma.Context) string {
	if t := bearerToken(ctx.Header("Authorization")); t != "" {
		return t
	}
	if c, err := huma.ReadCookie(ctx, sessionCookieName); err == nil && c != nil {
		return c.Value
	}
	return ""
}

// newAuthMiddleware returns Huma middleware that requires a valid session,
// set via AuthMiddleware on individual operations. On success it stores the
// authenticated user in the request context for userFromContext to read.
func newAuthMiddleware(api huma.API, queries db.Querier) func(huma.Context, func(huma.Context)) {
	return func(ctx huma.Context, next func(huma.Context)) {
		token := tokenFromRequest(ctx)
		if token == "" {
			huma.WriteErr(api, ctx, 401, "authentication required")
			return
		}

		row, err := queries.GetSessionAndUser(ctx.Context(), auth.HashSessionToken(token))
		if err != nil {
			if !errors.Is(err, pgx.ErrNoRows) {
				// Fail closed: an unreachable DB fails auth, not through.
				huma.WriteErr(api, ctx, 401, "authentication required")
				return
			}
			huma.WriteErr(api, ctx, 401, "session expired or invalid")
			return
		}

		// Best-effort; a failure to record activity shouldn't fail the request.
		_ = queries.TouchSession(ctx.Context(), auth.HashSessionToken(token))

		user := authedUser{ID: row.ID, Email: row.Email, Name: row.Name, Bio: row.Bio.String}
		newCtx := huma.WithValue(ctx, userCtxKey, user)
		newCtx = huma.WithValue(newCtx, tokenCtxKey, token)
		next(newCtx)
	}
}

// addAuth attaches the auth middleware to op, so it requires a valid
// session. Call it on the *huma.Operation value before huma.Register.
func addAuth(op *huma.Operation, api huma.API, queries db.Querier) {
	op.Middlewares = append(op.Middlewares, newAuthMiddleware(api, queries))
}

// tokenCtxKey holds the raw bearer/cookie token for the current request, so
// the logout handler can hash and delete the exact session that was used
// without re-parsing the request.
const tokenCtxKey ctxKey = "completed.token"

func tokenFromContext(ctx context.Context) string {
	t, _ := ctx.Value(tokenCtxKey).(string)
	return t
}