package postgres

import (
	"context"
	"errors"
	"fmt"

	"knowledge-governance/internal/governance"
)

const listReleasePlanSQL = `
WITH ` + releaseGateCTEs + `,
source_truth AS (
    SELECT source.id AS source_item_id, source.title, source.revision, source.source_change,
           -- 「禁止导入」记录在 source_items.policy_state 上；这里必须把它算进期望策略，
           -- 否则被禁止的条目会被当成"仍然保留"→ 生产侧已存在的它只会算出 unchanged，
           -- 永远不产生 delete 动作，生产知识无法通过发布通道下架
           -- （2026-10-10 实测：PDF 已 enabled 于生产库、policy_state=blocked，计划给的却是
           --  unchanged/present、can_release=false）。
           CASE WHEN source.policy_state='blocked' THEN 'blocked'
                ELSE COALESCE(item_rule.visibility, directory_rule.visibility, source.visibility) END AS desired_policy
    FROM source_items source
    LEFT JOIN source_item_scope_overrides item_rule ON item_rule.source_item_id=source.id
    LEFT JOIN LATERAL (
        SELECT rule.visibility
        FROM directory_scope_rules rule
        WHERE rule.source_connection_id=source.source_connection_id
          AND (rule.directory_path='' OR source.normalized_path=rule.directory_path OR source.normalized_path LIKE rule.directory_path||'/%')
        ORDER BY LENGTH(rule.directory_path) DESC
        LIMIT 1
    ) directory_rule ON TRUE
),
desired AS (
    SELECT truth.source_item_id, truth.title, scope.target_scope
    FROM source_truth truth
    CROSS JOIN LATERAL unnest(
        CASE
          WHEN truth.source_change='deleted' OR truth.desired_policy='blocked' THEN ARRAY[]::TEXT[]
          WHEN truth.desired_policy='both' THEN ARRAY['internal','external']::TEXT[]
          ELSE ARRAY[truth.desired_policy]::TEXT[]
        END
    ) scope(target_scope)
),
test_ready AS (
    SELECT DISTINCT ON (version.source_item_id, publication.target_scope)
           version.source_item_id, publication.target_scope, publication.id AS publication_id,
           ready.review_id AS release_revision
    FROM release_ready ready
    JOIN test_publications publication ON publication.id=ready.publication_id
    JOIN source_item_versions version ON version.id=publication.source_item_version_id
    ORDER BY version.source_item_id, publication.target_scope, publication.updated_at DESC, publication.id DESC
),
latest_production AS (
    SELECT DISTINCT ON (version.source_item_id, publication.target_scope)
           version.source_item_id, publication.target_scope,
           publication.id AS publication_id, item.production_revision
    FROM release_item_executions item
    JOIN release_executions execution ON execution.id=item.release_execution_id
    JOIN test_publications publication ON publication.id=item.publication_id
    JOIN source_item_versions version ON version.id=publication.source_item_version_id
    WHERE execution.state IN ('completed','rolled_back')
      AND item.state IN ('verified','rolled_back')
    ORDER BY version.source_item_id, publication.target_scope, execution.completed_at DESC NULLS LAST, execution.id DESC
),
production AS (
    SELECT * FROM latest_production WHERE production_revision<>'' AND production_revision<>'absent'
),
all_scopes AS (
    SELECT source_item_id,target_scope FROM desired
    UNION
    SELECT source_item_id,target_scope FROM production
),
plan AS (
    SELECT COALESCE(test.publication_id, production.publication_id, '') AS publication_id,
           truth.title,
           truth.source_change,
           scope.target_scope,
           CASE
             WHEN truth.source_change='unavailable' THEN 'blocked'
             WHEN desired.source_item_id IS NULL AND production.source_item_id IS NOT NULL THEN 'delete'
             WHEN desired.source_item_id IS NOT NULL AND test.publication_id IS NULL THEN 'blocked'
             WHEN production.source_item_id IS NULL THEN 'add'
             WHEN production.production_revision<>test.release_revision THEN 'update'
             ELSE 'unchanged'
           END AS action,
           CASE WHEN desired.source_item_id IS NULL THEN 'not_required' WHEN test.publication_id IS NULL THEN 'not_ready' ELSE 'ready' END AS test_state,
           CASE WHEN production.source_item_id IS NULL THEN 'absent' ELSE 'present' END AS production_state
    FROM all_scopes scope
    JOIN source_truth truth ON truth.source_item_id=scope.source_item_id
    LEFT JOIN desired ON desired.source_item_id=scope.source_item_id AND desired.target_scope=scope.target_scope
    LEFT JOIN test_ready test ON test.source_item_id=scope.source_item_id AND test.target_scope=scope.target_scope
    LEFT JOIN production ON production.source_item_id=scope.source_item_id AND production.target_scope=scope.target_scope
)
SELECT publication_id,title,target_scope,action,test_state,production_state,
       action IN ('add', 'update', 'delete') AS can_release,
       CASE WHEN action='blocked' AND source_change='unavailable' THEN 'source_unavailable'
            WHEN action='blocked' THEN 'test_not_ready'
            ELSE '' END AS blocker
FROM plan
ORDER BY CASE action WHEN 'delete' THEN 0 WHEN 'blocked' THEN 1 WHEN 'update' THEN 2 WHEN 'add' THEN 3 ELSE 4 END, title, target_scope
`

func (s *Store) ListReleasePlan(ctx context.Context) (governance.ReleasePlan, error) {
	rows, err := s.db.Query(ctx, listReleasePlanSQL)
	if err != nil {
		return governance.ReleasePlan{}, fmt.Errorf("list release plan: %w", err)
	}
	defer rows.Close()
	plan := governance.ReleasePlan{Items: []governance.ReleasePlanItem{}}
	for rows.Next() {
		var item governance.ReleasePlanItem
		if err := rows.Scan(&item.PublicationID, &item.Title, &item.TargetScope, &item.Action, &item.TestState, &item.ProductionState, &item.CanRelease, &item.Blocker); err != nil {
			return governance.ReleasePlan{}, fmt.Errorf("scan release plan: %w", err)
		}
		if (item.TargetScope != "internal" && item.TargetScope != "external") || (item.Action != "add" && item.Action != "update" && item.Action != "delete" && item.Action != "blocked" && item.Action != "unchanged") {
			return governance.ReleasePlan{}, errors.New("invalid release plan row")
		}
		switch item.Action {
		case "add":
			plan.Summary.Add++
		case "update":
			plan.Summary.Update++
		case "delete":
			plan.Summary.Delete++
		case "unchanged":
			plan.Summary.Unchanged++
			continue
		}
		if !item.CanRelease {
			plan.Summary.Blocked++
		}
		plan.Items = append(plan.Items, item)
	}
	if err := rows.Err(); err != nil {
		return governance.ReleasePlan{}, fmt.Errorf("iterate release plan: %w", err)
	}
	return plan, nil
}