package postgres

import (
	"context"
	"encoding/json"
	"fmt"

	"git.gobha.me/xcaliber/chat-switchboard/models"
)

// WorkflowStore implements store.WorkflowStore for Postgres.
type WorkflowStore struct{}

func NewWorkflowStore() *WorkflowStore { return &WorkflowStore{} }

// ── Workflow CRUD ───────────────────────────

func (s *WorkflowStore) Create(ctx context.Context, w *models.Workflow) error {
	branding := jsonOrEmpty(w.Branding)
	retention := jsonOrDefault(w.Retention, `{"mode":"archive"}`)
	return DB.QueryRowContext(ctx, `
		INSERT INTO workflows (team_id, name, slug, description, branding, entry_mode, is_active, on_complete, retention, created_by)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
		RETURNING id, version, created_at, updated_at`,
		w.TeamID, w.Name, w.Slug, w.Description, branding, w.EntryMode,
		w.IsActive, jsonOrNull(w.OnComplete), retention, w.CreatedBy,
	).Scan(&w.ID, &w.Version, &w.CreatedAt, &w.UpdatedAt)
}

func (s *WorkflowStore) GetByID(ctx context.Context, id string) (*models.Workflow, error) {
	w := &models.Workflow{}
	var branding, retention, onComplete []byte
	err := DB.QueryRowContext(ctx, `
		SELECT id, team_id, name, slug, description, branding, entry_mode, is_active,
		       version, on_complete, retention, created_by, created_at, updated_at
		FROM workflows WHERE id = $1`, id,
	).Scan(&w.ID, &w.TeamID, &w.Name, &w.Slug, &w.Description, &branding,
		&w.EntryMode, &w.IsActive, &w.Version, &onComplete, &retention,
		&w.CreatedBy, &w.CreatedAt, &w.UpdatedAt)
	if err != nil {
		return nil, err
	}
	w.Branding = branding
	w.OnComplete = onComplete
	w.Retention = retention
	return w, nil
}

func (s *WorkflowStore) GetBySlug(ctx context.Context, teamID *string, slug string) (*models.Workflow, error) {
	var q string
	var args []interface{}
	if teamID != nil {
		q = `SELECT id, team_id, name, slug, description, branding, entry_mode, is_active,
		            version, on_complete, retention, created_by, created_at, updated_at
		     FROM workflows WHERE team_id = $1 AND slug = $2`
		args = []interface{}{*teamID, slug}
	} else {
		q = `SELECT id, team_id, name, slug, description, branding, entry_mode, is_active,
		            version, on_complete, retention, created_by, created_at, updated_at
		     FROM workflows WHERE team_id IS NULL AND slug = $1`
		args = []interface{}{slug}
	}
	w := &models.Workflow{}
	var branding, retention, onComplete []byte
	err := DB.QueryRowContext(ctx, q, args...).Scan(
		&w.ID, &w.TeamID, &w.Name, &w.Slug, &w.Description, &branding,
		&w.EntryMode, &w.IsActive, &w.Version, &onComplete, &retention,
		&w.CreatedBy, &w.CreatedAt, &w.UpdatedAt)
	if err != nil {
		return nil, err
	}
	w.Branding = branding
	w.OnComplete = onComplete
	w.Retention = retention
	return w, nil
}

func (s *WorkflowStore) Update(ctx context.Context, id string, patch models.WorkflowPatch) error {
	// Build dynamic SET clause
	sets := []string{}
	args := []interface{}{}
	idx := 1

	add := func(col string, val interface{}) {
		sets = append(sets, fmt.Sprintf("%s = $%d", col, idx))
		args = append(args, val)
		idx++
	}

	if patch.Name != nil {
		add("name", *patch.Name)
	}
	if patch.Description != nil {
		add("description", *patch.Description)
	}
	if patch.Branding != nil {
		add("branding", string(*patch.Branding))
	}
	if patch.EntryMode != nil {
		add("entry_mode", *patch.EntryMode)
	}
	if patch.IsActive != nil {
		add("is_active", *patch.IsActive)
	}
	if patch.OnComplete != nil {
		add("on_complete", string(*patch.OnComplete))
	}
	if patch.Retention != nil {
		add("retention", string(*patch.Retention))
	}

	if len(sets) == 0 {
		return nil
	}

	// Increment version on any edit
	sets = append(sets, fmt.Sprintf("version = version + 1"))

	q := "UPDATE workflows SET "
	for i, s := range sets {
		if i > 0 {
			q += ", "
		}
		q += s
	}
	q += fmt.Sprintf(" WHERE id = $%d", idx)
	args = append(args, id)

	_, err := DB.ExecContext(ctx, q, args...)
	return err
}

func (s *WorkflowStore) Delete(ctx context.Context, id string) error {
	_, err := DB.ExecContext(ctx, `DELETE FROM workflows WHERE id = $1`, id)
	return err
}

func (s *WorkflowStore) ListForTeam(ctx context.Context, teamID string) ([]models.Workflow, error) {
	return s.queryWorkflows(ctx, `
		SELECT id, team_id, name, slug, description, branding, entry_mode, is_active,
		       version, on_complete, retention, created_by, created_at, updated_at
		FROM workflows WHERE team_id = $1
		ORDER BY name ASC`, teamID)
}

func (s *WorkflowStore) ListGlobal(ctx context.Context) ([]models.Workflow, error) {
	return s.queryWorkflows(ctx, `
		SELECT id, team_id, name, slug, description, branding, entry_mode, is_active,
		       version, on_complete, retention, created_by, created_at, updated_at
		FROM workflows WHERE team_id IS NULL
		ORDER BY name ASC`)
}

func (s *WorkflowStore) queryWorkflows(ctx context.Context, q string, args ...interface{}) ([]models.Workflow, error) {
	rows, err := DB.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []models.Workflow
	for rows.Next() {
		var w models.Workflow
		var branding, retention, onComplete []byte
		if err := rows.Scan(&w.ID, &w.TeamID, &w.Name, &w.Slug, &w.Description,
			&branding, &w.EntryMode, &w.IsActive, &w.Version, &onComplete,
			&retention, &w.CreatedBy, &w.CreatedAt, &w.UpdatedAt); err != nil {
			return nil, err
		}
		w.Branding = branding
		w.OnComplete = onComplete
		w.Retention = retention
		result = append(result, w)
	}
	return result, rows.Err()
}

// ── Stages ──────────────────────────────────

func (s *WorkflowStore) CreateStage(ctx context.Context, st *models.WorkflowStage) error {
	formTpl := jsonOrEmpty(st.FormTemplate)
	transRules := jsonOrEmpty(st.TransitionRules)
	return DB.QueryRowContext(ctx, `
		INSERT INTO workflow_stages (workflow_id, ordinal, name, persona_id, assignment_team_id,
		            form_template, history_mode, auto_transition, transition_rules)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
		RETURNING id, created_at`,
		st.WorkflowID, st.Ordinal, st.Name, st.PersonaID, st.AssignmentTeamID,
		formTpl, st.HistoryMode, st.AutoTransition, transRules,
	).Scan(&st.ID, &st.CreatedAt)
}

func (s *WorkflowStore) ListStages(ctx context.Context, workflowID string) ([]models.WorkflowStage, error) {
	rows, err := DB.QueryContext(ctx, `
		SELECT id, workflow_id, ordinal, name, persona_id, assignment_team_id,
		       form_template, history_mode, auto_transition, transition_rules, created_at
		FROM workflow_stages WHERE workflow_id = $1
		ORDER BY ordinal ASC`, workflowID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var result []models.WorkflowStage
	for rows.Next() {
		var st models.WorkflowStage
		var formTpl, transRules []byte
		if err := rows.Scan(&st.ID, &st.WorkflowID, &st.Ordinal, &st.Name,
			&st.PersonaID, &st.AssignmentTeamID, &formTpl, &st.HistoryMode,
			&st.AutoTransition, &transRules, &st.CreatedAt); err != nil {
			return nil, err
		}
		st.FormTemplate = formTpl
		st.TransitionRules = transRules
		result = append(result, st)
	}
	return result, rows.Err()
}

func (s *WorkflowStore) UpdateStage(ctx context.Context, st *models.WorkflowStage) error {
	formTpl := jsonOrEmpty(st.FormTemplate)
	transRules := jsonOrEmpty(st.TransitionRules)
	_, err := DB.ExecContext(ctx, `
		UPDATE workflow_stages
		SET ordinal = $2, name = $3, persona_id = $4, assignment_team_id = $5,
		    form_template = $6, history_mode = $7, auto_transition = $8, transition_rules = $9
		WHERE id = $1`,
		st.ID, st.Ordinal, st.Name, st.PersonaID, st.AssignmentTeamID,
		formTpl, st.HistoryMode, st.AutoTransition, transRules)
	return err
}

func (s *WorkflowStore) DeleteStage(ctx context.Context, id string) error {
	_, err := DB.ExecContext(ctx, `DELETE FROM workflow_stages WHERE id = $1`, id)
	return err
}

func (s *WorkflowStore) ReorderStages(ctx context.Context, workflowID string, orderedIDs []string) error {
	tx, err := DB.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer tx.Rollback()

	for i, id := range orderedIDs {
		if _, err := tx.ExecContext(ctx, `
			UPDATE workflow_stages SET ordinal = $1 WHERE id = $2 AND workflow_id = $3`,
			i, id, workflowID); err != nil {
			return err
		}
	}
	return tx.Commit()
}

// ── Versions ────────────────────────────────

func (s *WorkflowStore) Publish(ctx context.Context, v *models.WorkflowVersion) error {
	return DB.QueryRowContext(ctx, `
		INSERT INTO workflow_versions (workflow_id, version_number, snapshot)
		VALUES ($1, $2, $3)
		RETURNING id, created_at`,
		v.WorkflowID, v.VersionNumber, string(v.Snapshot),
	).Scan(&v.ID, &v.CreatedAt)
}

func (s *WorkflowStore) GetVersion(ctx context.Context, workflowID string, versionNumber int) (*models.WorkflowVersion, error) {
	v := &models.WorkflowVersion{}
	var snapshot []byte
	err := DB.QueryRowContext(ctx, `
		SELECT id, workflow_id, version_number, snapshot, created_at
		FROM workflow_versions WHERE workflow_id = $1 AND version_number = $2`,
		workflowID, versionNumber,
	).Scan(&v.ID, &v.WorkflowID, &v.VersionNumber, &snapshot, &v.CreatedAt)
	if err != nil {
		return nil, err
	}
	v.Snapshot = snapshot
	return v, nil
}

func (s *WorkflowStore) GetLatestVersion(ctx context.Context, workflowID string) (*models.WorkflowVersion, error) {
	v := &models.WorkflowVersion{}
	var snapshot []byte
	err := DB.QueryRowContext(ctx, `
		SELECT id, workflow_id, version_number, snapshot, created_at
		FROM workflow_versions WHERE workflow_id = $1
		ORDER BY version_number DESC LIMIT 1`,
		workflowID,
	).Scan(&v.ID, &v.WorkflowID, &v.VersionNumber, &snapshot, &v.CreatedAt)
	if err != nil {
		return nil, err
	}
	v.Snapshot = snapshot
	return v, nil
}

// ── Helpers ─────────────────────────────────

func jsonOrEmpty(b json.RawMessage) string {
	if len(b) == 0 {
		return "{}"
	}
	return string(b)
}

func jsonOrDefault(b json.RawMessage, def string) string {
	if len(b) == 0 {
		return def
	}
	return string(b)
}

func jsonOrNull(b json.RawMessage) interface{} {
	if len(b) == 0 || string(b) == "null" {
		return nil
	}
	return string(b)
}