package service

import (
	"context"
	"strings"

	"gitea.stevedudenhoeffer.com/steve/pansy/internal/agentmodel"
	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
)

// Instance settings (#79): admin-editable, instance-wide configuration. The
// admin gate lives HERE, in the seam, not in the handler — the same rule every
// other permission follows. The API's requireAdmin middleware is a cheap early
// 403, not the authority.

// requireAdmin returns nil iff the actor is an admin, else ErrForbidden.
//
// ErrForbidden, not ErrNotFound: settings are not a resource whose existence is
// masked. A logged-in non-admin knows the instance has settings; they simply may
// not touch them. (Contrast objects/lots, where no-access masks existence.)
func (s *Service) requireAdmin(ctx context.Context, actorID int64) error {
	u, err := s.store.GetUserByID(ctx, actorID)
	if err != nil {
		return err
	}
	if !u.IsAdmin {
		return domain.ErrForbidden
	}
	return nil
}

// GetInstanceSettings returns the instance settings for an admin.
func (s *Service) GetInstanceSettings(ctx context.Context, actorID int64) (*domain.InstanceSettings, error) {
	if err := s.requireAdmin(ctx, actorID); err != nil {
		return nil, err
	}
	return s.store.GetInstanceSettings(ctx)
}

// InstanceSettingsPatch is a full replacement of the editable fields plus the
// current version. Both agent fields carry their "inherit" sentinel: an empty
// AgentModel means fall back to env, a nil AgentEnabled means inherit.
type InstanceSettingsPatch struct {
	AgentModel   string
	AgentEnabled *bool
	VisionModel  string
	Version      int64
}

// UpdateInstanceSettings applies an admin's change, version-guarded. It returns
// (current row, ErrVersionConflict) on a stale version, like every mutable
// resource. The model spec is validated before it is stored, so a typo is a 400
// now rather than a broken assistant on the next turn.
//
// It does NOT rebuild the running agent — that is the API layer's job, because
// the live Runner lives there. The caller rebuilds on success.
func (s *Service) UpdateInstanceSettings(ctx context.Context, actorID int64, patch InstanceSettingsPatch) (*domain.InstanceSettings, error) {
	if err := s.requireAdmin(ctx, actorID); err != nil {
		return nil, err
	}
	model := strings.TrimSpace(patch.AgentModel)
	vision := strings.TrimSpace(patch.VisionModel)
	// Validate non-empty specs up front. An empty one is the "inherit env"
	// sentinel and needs no check — the env value was validated at boot.
	for _, spec := range []string{model, vision} {
		if spec != "" {
			if err := agentmodel.Validate(s.cfg.Agent.OllamaCloudAPIKey, spec); err != nil {
				return nil, domain.ErrInvalidInput
			}
		}
	}
	return s.store.UpdateInstanceSettings(ctx, &domain.InstanceSettings{
		AgentModel:   model,
		AgentEnabled: patch.AgentEnabled,
		VisionModel:  vision,
		Version:      patch.Version,
	})
}

// EffectiveAgent resolves the agent configuration actually in force: DB settings
// override the environment, and the API key always comes from the environment.
//
// This is internal plumbing (the API layer calls it to build the Runner), NOT an
// admin-gated operation — resolving what's configured is not the same as editing
// it, and the agent bootstrap must work before any user is even authenticated.
type EffectiveAgent struct {
	Model   string
	Enabled bool
	APIKey  string
}

// Ready mirrors config.AgentConfig.Ready: enabled, with a key and a model.
func (e EffectiveAgent) Ready() bool {
	return e.Enabled && e.APIKey != "" && e.Model != ""
}

// EffectiveAgent reads the settings row and layers it over the environment.
func (s *Service) EffectiveAgent(ctx context.Context) (EffectiveAgent, error) {
	st, err := s.store.GetInstanceSettings(ctx)
	if err != nil {
		return EffectiveAgent{}, err
	}
	eff := EffectiveAgent{
		Model:   s.cfg.Agent.Model,
		Enabled: s.cfg.Agent.Enabled,
		APIKey:  s.cfg.Agent.OllamaCloudAPIKey,
	}
	if st.AgentModel != "" {
		eff.Model = st.AgentModel
	}
	if st.AgentEnabled != nil {
		eff.Enabled = *st.AgentEnabled
	}
	return eff, nil
}

// EffectiveVision resolves the vision configuration in force for seed-packet
// capture (#81): the model from DB-over-env, the key always from env.
type EffectiveVision struct {
	Model  string
	APIKey string
}

// Ready reports whether packet capture can be offered: a key and a vision model.
// There's no separate enabled flag — configuring a vision model IS enabling it.
func (e EffectiveVision) Ready() bool {
	return e.APIKey != "" && e.Model != ""
}

// EffectiveVision reads the settings row and layers it over the environment.
func (s *Service) EffectiveVision(ctx context.Context) (EffectiveVision, error) {
	st, err := s.store.GetInstanceSettings(ctx)
	if err != nil {
		return EffectiveVision{}, err
	}
	eff := EffectiveVision{
		Model:  s.cfg.Agent.VisionModel,
		APIKey: s.cfg.Agent.OllamaCloudAPIKey,
	}
	if st.VisionModel != "" {
		eff.Model = st.VisionModel
	}
	return eff, nil
}