package postgres

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"time"

	"chat-switchboard/models"
	"chat-switchboard/store"
)

// 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, webhook_url, webhook_secret, created_by)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)
		RETURNING id, version, created_at, updated_at`,
		w.TeamID, w.Name, w.Slug, w.Description, branding, w.EntryMode,
		w.IsActive, jsonOrNull(w.OnComplete), retention,
		nullIfEmpty(w.WebhookURL), nullIfEmpty(w.WebhookSecret), 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
	var webhookURL, webhookSecret *string
	err := DB.QueryRowContext(ctx, `
		SELECT id, team_id, name, slug, description, branding, entry_mode, is_active,
		       version, on_complete, retention, webhook_url, webhook_secret,
		       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,
		&webhookURL, &webhookSecret,
		&w.CreatedBy, &w.CreatedAt, &w.UpdatedAt)
	if err != nil {
		return nil, err
	}
	w.Branding = branding
	w.OnComplete = onComplete
	w.Retention = retention
	if webhookURL != nil {
		w.WebhookURL = *webhookURL
	}
	if webhookSecret != nil {
		w.WebhookSecret = *webhookSecret
	}
	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, webhook_url, webhook_secret,
		            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, webhook_url, webhook_secret,
		            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
	var webhookURL, webhookSecret *string
	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,
		&webhookURL, &webhookSecret,
		&w.CreatedBy, &w.CreatedAt, &w.UpdatedAt)
	if err != nil {
		return nil, err
	}
	w.Branding = branding
	w.OnComplete = onComplete
	w.Retention = retention
	if webhookURL != nil {
		w.WebhookURL = *webhookURL
	}
	if webhookSecret != nil {
		w.WebhookSecret = *webhookSecret
	}
	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 patch.WebhookURL != nil {
		add("webhook_url", *patch.WebhookURL)
	}
	if patch.WebhookSecret != nil {
		add("webhook_secret", *patch.WebhookSecret)
	}

	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, webhook_url, webhook_secret,
		       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, webhook_url, webhook_secret,
		       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
		var webhookURL, webhookSecret *string
		if err := rows.Scan(&w.ID, &w.TeamID, &w.Name, &w.Slug, &w.Description,
			&branding, &w.EntryMode, &w.IsActive, &w.Version, &onComplete,
			&retention, &webhookURL, &webhookSecret,
			&w.CreatedBy, &w.CreatedAt, &w.UpdatedAt); err != nil {
			return nil, err
		}
		w.Branding = branding
		w.OnComplete = onComplete
		w.Retention = retention
		if webhookURL != nil {
			w.WebhookURL = *webhookURL
		}
		if webhookSecret != nil {
			w.WebhookSecret = *webhookSecret
		}
		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)
	stageMode := st.StageMode
	if stageMode == "" {
		stageMode = models.StageModeChatOnly
	}
	return DB.QueryRowContext(ctx, `
		INSERT INTO workflow_stages (workflow_id, ordinal, name, persona_id, assignment_team_id,
		            form_template, stage_mode, history_mode, auto_transition, transition_rules,
		            surface_pkg_id, sla_seconds)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)
		RETURNING id, created_at`,
		st.WorkflowID, st.Ordinal, st.Name, st.PersonaID, st.AssignmentTeamID,
		formTpl, stageMode, st.HistoryMode, st.AutoTransition, transRules, st.SurfacePkgID,
		st.SLASeconds,
	).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, stage_mode, history_mode, auto_transition, transition_rules,
		       surface_pkg_id, sla_seconds, 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.StageMode,
			&st.HistoryMode, &st.AutoTransition, &transRules,
			&st.SurfacePkgID, &st.SLASeconds, &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)
	stageMode := st.StageMode
	if stageMode == "" {
		stageMode = models.StageModeChatOnly
	}
	_, err := DB.ExecContext(ctx, `
		UPDATE workflow_stages
		SET ordinal = $2, name = $3, persona_id = $4, assignment_team_id = $5,
		    form_template = $6, stage_mode = $7, history_mode = $8, auto_transition = $9,
		    transition_rules = $10, surface_pkg_id = $11, sla_seconds = $12
		WHERE id = $1`,
		st.ID, st.Ordinal, st.Name, st.PersonaID, st.AssignmentTeamID,
		formTpl, stageMode, st.HistoryMode, st.AutoTransition, transRules, st.SurfacePkgID,
		st.SLASeconds)
	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)
}

func nullIfEmpty(s string) interface{} {
	if s == "" {
		return nil
	}
	return s
}

// ── Assignments (v0.29.0-cs3) ───────────────────────────────────────────

func (s *WorkflowStore) CreateAssignment(ctx context.Context, a *store.WorkflowAssignment) error {
	a.ID = store.NewID()
	_, err := DB.ExecContext(ctx, `
		INSERT INTO workflow_assignments (id, channel_id, stage, team_id)
		VALUES ($1, $2, $3, $4)
	`, a.ID, a.ChannelID, a.Stage, a.TeamID)
	return err
}

func (s *WorkflowStore) ListAssignmentsForTeam(ctx context.Context, teamID, status string) ([]store.WorkflowAssignment, error) {
	rows, err := DB.QueryContext(ctx, `
		SELECT id, channel_id, stage, team_id, assigned_to, status,
		       created_at, claimed_at, completed_at
		FROM workflow_assignments
		WHERE team_id = $1 AND status = $2
		ORDER BY created_at DESC
	`, teamID, status)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return scanAssignments(rows)
}

func (s *WorkflowStore) ListAssignmentsMine(ctx context.Context, userID string) ([]store.WorkflowAssignment, error) {
	rows, err := DB.QueryContext(ctx, `
		SELECT DISTINCT wa.id, wa.channel_id, wa.stage, wa.team_id, wa.assigned_to, wa.status,
		       wa.created_at, wa.claimed_at, wa.completed_at
		FROM workflow_assignments wa
		LEFT JOIN team_members tm ON tm.team_id = wa.team_id AND tm.user_id = $1
		WHERE (wa.assigned_to = $2 AND wa.status = 'claimed')
		   OR (wa.status = 'unassigned' AND tm.user_id IS NOT NULL)
		ORDER BY wa.created_at DESC
	`, userID, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return scanAssignments(rows)
}

func (s *WorkflowStore) ClaimAssignment(ctx context.Context, assignmentID, userID string) (int64, error) {
	res, err := DB.ExecContext(ctx, `
		UPDATE workflow_assignments
		SET assigned_to = $1, status = 'claimed', claimed_at = $2
		WHERE id = $3 AND status = 'unassigned'
	`, userID, time.Now().UTC(), assignmentID)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

func (s *WorkflowStore) CompleteAssignment(ctx context.Context, assignmentID string) (int64, error) {
	res, err := DB.ExecContext(ctx, `
		UPDATE workflow_assignments
		SET status = 'completed', completed_at = $1
		WHERE id = $2 AND status = 'claimed'
	`, time.Now().UTC(), assignmentID)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

func (s *WorkflowStore) GetAssignmentChannelID(ctx context.Context, assignmentID string) (string, error) {
	var channelID string
	err := DB.QueryRowContext(ctx,
		`SELECT channel_id FROM workflow_assignments WHERE id = $1`, assignmentID).Scan(&channelID)
	return channelID, err
}

func (s *WorkflowStore) TryRoundRobin(ctx context.Context, teamID, assignmentID string) (string, error) {
	// Find least-recently-assigned team member
	rows, err := DB.QueryContext(ctx, `
		SELECT m.user_id, COALESCE(MAX(wa.claimed_at), '1970-01-01T00:00:00Z') as last_claim
		FROM team_members m
		LEFT JOIN workflow_assignments wa ON wa.assigned_to = m.user_id AND wa.team_id = $1
		WHERE m.team_id = $2
		GROUP BY m.user_id
		ORDER BY last_claim ASC
		LIMIT 1
	`, teamID, teamID)
	if err != nil {
		return "", err
	}
	defer rows.Close()

	if !rows.Next() {
		return "", nil // no team members
	}
	var userID, lastClaim string
	if err := rows.Scan(&userID, &lastClaim); err != nil {
		return "", err
	}

	// Claim for that user
	_, err = DB.ExecContext(ctx, `
		UPDATE workflow_assignments
		SET assigned_to = $1, status = 'claimed', claimed_at = $2
		WHERE id = $3 AND status = 'unassigned'
	`, userID, time.Now().UTC(), assignmentID)
	if err != nil {
		return "", err
	}
	return userID, nil
}

func scanAssignments(rows *sql.Rows) ([]store.WorkflowAssignment, error) {
	var result []store.WorkflowAssignment
	for rows.Next() {
		var a store.WorkflowAssignment
		if err := rows.Scan(&a.ID, &a.ChannelID, &a.Stage, &a.TeamID,
			&a.AssignedTo, &a.Status, &a.CreatedAt, &a.ClaimedAt, &a.CompletedAt); err != nil {
			return nil, err
		}
		result = append(result, a)
	}
	if result == nil {
		result = []store.WorkflowAssignment{}
	}
	return result, rows.Err()
}

// ── Review Comments (v0.35.0) ───────────────────────────

func (s *WorkflowStore) GetAssignmentByID(ctx context.Context, id string) (*store.WorkflowAssignment, error) {
	var a store.WorkflowAssignment
	var rc []byte
	err := DB.QueryRowContext(ctx, `
		SELECT id, channel_id, stage, team_id, assigned_to, status,
		       review_comments, created_at, claimed_at, completed_at
		FROM workflow_assignments WHERE id = $1
	`, id).Scan(&a.ID, &a.ChannelID, &a.Stage, &a.TeamID, &a.AssignedTo, &a.Status,
		&rc, &a.CreatedAt, &a.ClaimedAt, &a.CompletedAt)
	if err != nil {
		return nil, err
	}
	a.ReviewComments = rc
	return &a, nil
}

func (s *WorkflowStore) AddReviewComment(ctx context.Context, assignmentID string, comment store.ReviewComment) error {
	commentJSON, err := json.Marshal(comment)
	if err != nil {
		return err
	}
	_, err = DB.ExecContext(ctx, `
		UPDATE workflow_assignments
		SET review_comments = review_comments || $1::jsonb
		WHERE id = $2
	`, "["+string(commentJSON)+"]", assignmentID)
	return err
}