'use strict';

const { assertValidEntity } = require('./schema');

const ACTIVE_SESSION_STATES = ['active', 'running', 'idle'];
const SUCCESS_OUTCOMES = new Set(['success', 'succeeded', 'passed']);
const FAILURE_OUTCOMES = new Set(['failure', 'failed', 'error']);

function normalizeLimit(value, fallback) {
  if (value === undefined || value === null) {
    return fallback;
  }

  const parsed = Number.parseInt(value, 10);
  if (!Number.isFinite(parsed) || parsed <= 0) {
    throw new Error(`Invalid limit: ${value}`);
  }

  return parsed;
}

function parseJsonColumn(value, fallback) {
  if (value === null || value === undefined || value === '') {
    return fallback;
  }

  return JSON.parse(value);
}

function stringifyJson(value, label) {
  try {
    return JSON.stringify(value);
  } catch (error) {
    throw new Error(`Failed to serialize ${label}: ${error.message}`);
  }
}

function mapSessionRow(row) {
  const snapshot = parseJsonColumn(row.snapshot, {});
  return {
    id: row.id,
    adapterId: row.adapter_id,
    harness: row.harness,
    state: row.state,
    repoRoot: row.repo_root,
    startedAt: row.started_at,
    endedAt: row.ended_at,
    snapshot,
    workerCount: Array.isArray(snapshot && snapshot.workers) ? snapshot.workers.length : 0,
  };
}

function mapSkillRunRow(row) {
  return {
    id: row.id,
    skillId: row.skill_id,
    skillVersion: row.skill_version,
    sessionId: row.session_id,
    taskDescription: row.task_description,
    outcome: row.outcome,
    failureReason: row.failure_reason,
    tokensUsed: row.tokens_used,
    durationMs: row.duration_ms,
    userFeedback: row.user_feedback,
    createdAt: row.created_at,
  };
}

function mapSkillVersionRow(row) {
  return {
    skillId: row.skill_id,
    version: row.version,
    contentHash: row.content_hash,
    amendmentReason: row.amendment_reason,
    promotedAt: row.promoted_at,
    rolledBackAt: row.rolled_back_at,
  };
}

function mapDecisionRow(row) {
  return {
    id: row.id,
    sessionId: row.session_id,
    title: row.title,
    rationale: row.rationale,
    alternatives: parseJsonColumn(row.alternatives, []),
    supersedes: row.supersedes,
    status: row.status,
    createdAt: row.created_at,
  };
}

function mapInstallStateRow(row) {
  const modules = parseJsonColumn(row.modules, []);
  const operations = parseJsonColumn(row.operations, []);
  const status = row.source_version && row.installed_at ? 'healthy' : 'warning';

  return {
    targetId: row.target_id,
    targetRoot: row.target_root,
    profile: row.profile,
    modules,
    operations,
    installedAt: row.installed_at,
    sourceVersion: row.source_version,
    moduleCount: Array.isArray(modules) ? modules.length : 0,
    operationCount: Array.isArray(operations) ? operations.length : 0,
    status,
  };
}

function mapGovernanceEventRow(row) {
  return {
    id: row.id,
    sessionId: row.session_id,
    eventType: row.event_type,
    payload: parseJsonColumn(row.payload, null),
    resolvedAt: row.resolved_at,
    resolution: row.resolution,
    createdAt: row.created_at,
  };
}

function classifyOutcome(outcome) {
  const normalized = String(outcome || '').toLowerCase();
  if (SUCCESS_OUTCOMES.has(normalized)) {
    return 'success';
  }

  if (FAILURE_OUTCOMES.has(normalized)) {
    return 'failure';
  }

  return 'unknown';
}

function toPercent(numerator, denominator) {
  if (denominator === 0) {
    return null;
  }

  return Number(((numerator / denominator) * 100).toFixed(1));
}

function summarizeSkillRuns(skillRuns) {
  const summary = {
    totalCount: skillRuns.length,
    knownCount: 0,
    successCount: 0,
    failureCount: 0,
    unknownCount: 0,
    successRate: null,
    failureRate: null,
  };

  for (const skillRun of skillRuns) {
    const classification = classifyOutcome(skillRun.outcome);
    if (classification === 'success') {
      summary.successCount += 1;
      summary.knownCount += 1;
    } else if (classification === 'failure') {
      summary.failureCount += 1;
      summary.knownCount += 1;
    } else {
      summary.unknownCount += 1;
    }
  }

  summary.successRate = toPercent(summary.successCount, summary.knownCount);
  summary.failureRate = toPercent(summary.failureCount, summary.knownCount);
  return summary;
}

function summarizeInstallHealth(installations) {
  if (installations.length === 0) {
    return {
      status: 'missing',
      totalCount: 0,
      healthyCount: 0,
      warningCount: 0,
      installations: [],
    };
  }

  const summary = installations.reduce((result, installation) => {
    if (installation.status === 'healthy') {
      result.healthyCount += 1;
    } else {
      result.warningCount += 1;
    }
    return result;
  }, {
    totalCount: installations.length,
    healthyCount: 0,
    warningCount: 0,
  });

  return {
    status: summary.warningCount > 0 ? 'warning' : 'healthy',
    ...summary,
    installations,
  };
}

function normalizeSessionInput(session) {
  return {
    id: session.id,
    adapterId: session.adapterId,
    harness: session.harness,
    state: session.state,
    repoRoot: session.repoRoot ?? null,
    startedAt: session.startedAt ?? null,
    endedAt: session.endedAt ?? null,
    snapshot: session.snapshot ?? {},
  };
}

function normalizeSkillRunInput(skillRun) {
  return {
    id: skillRun.id,
    skillId: skillRun.skillId,
    skillVersion: skillRun.skillVersion,
    sessionId: skillRun.sessionId,
    taskDescription: skillRun.taskDescription,
    outcome: skillRun.outcome,
    failureReason: skillRun.failureReason ?? null,
    tokensUsed: skillRun.tokensUsed ?? null,
    durationMs: skillRun.durationMs ?? null,
    userFeedback: skillRun.userFeedback ?? null,
    createdAt: skillRun.createdAt || new Date().toISOString(),
  };
}

function normalizeSkillVersionInput(skillVersion) {
  return {
    skillId: skillVersion.skillId,
    version: skillVersion.version,
    contentHash: skillVersion.contentHash,
    amendmentReason: skillVersion.amendmentReason ?? null,
    promotedAt: skillVersion.promotedAt ?? null,
    rolledBackAt: skillVersion.rolledBackAt ?? null,
  };
}

function normalizeDecisionInput(decision) {
  return {
    id: decision.id,
    sessionId: decision.sessionId,
    title: decision.title,
    rationale: decision.rationale,
    alternatives: decision.alternatives === undefined || decision.alternatives === null
      ? []
      : decision.alternatives,
    supersedes: decision.supersedes ?? null,
    status: decision.status,
    createdAt: decision.createdAt || new Date().toISOString(),
  };
}

function normalizeInstallStateInput(installState) {
  return {
    targetId: installState.targetId,
    targetRoot: installState.targetRoot,
    profile: installState.profile ?? null,
    modules: installState.modules === undefined || installState.modules === null
      ? []
      : installState.modules,
    operations: installState.operations === undefined || installState.operations === null
      ? []
      : installState.operations,
    installedAt: installState.installedAt || new Date().toISOString(),
    sourceVersion: installState.sourceVersion ?? null,
  };
}

function normalizeGovernanceEventInput(governanceEvent) {
  return {
    id: governanceEvent.id,
    sessionId: governanceEvent.sessionId ?? null,
    eventType: governanceEvent.eventType,
    payload: governanceEvent.payload ?? null,
    resolvedAt: governanceEvent.resolvedAt ?? null,
    resolution: governanceEvent.resolution ?? null,
    createdAt: governanceEvent.createdAt || new Date().toISOString(),
  };
}

function createQueryApi(db) {
  const listRecentSessionsStatement = db.prepare(`
    SELECT *
    FROM sessions
    ORDER BY COALESCE(started_at, ended_at, '') DESC, id DESC
    LIMIT ?
  `);
  const countSessionsStatement = db.prepare(`
    SELECT COUNT(*) AS total_count
    FROM sessions
  `);
  const getSessionStatement = db.prepare(`
    SELECT *
    FROM sessions
    WHERE id = ?
  `);
  const getSessionSkillRunsStatement = db.prepare(`
    SELECT *
    FROM skill_runs
    WHERE session_id = ?
    ORDER BY created_at DESC, id DESC
  `);
  const getSessionDecisionsStatement = db.prepare(`
    SELECT *
    FROM decisions
    WHERE session_id = ?
    ORDER BY created_at DESC, id DESC
  `);
  const listActiveSessionsStatement = db.prepare(`
    SELECT *
    FROM sessions
    WHERE ended_at IS NULL
      AND state IN ('active', 'running', 'idle')
    ORDER BY COALESCE(started_at, ended_at, '') DESC, id DESC
    LIMIT ?
  `);
  const countActiveSessionsStatement = db.prepare(`
    SELECT COUNT(*) AS total_count
    FROM sessions
    WHERE ended_at IS NULL
      AND state IN ('active', 'running', 'idle')
  `);
  const listRecentSkillRunsStatement = db.prepare(`
    SELECT *
    FROM skill_runs
    ORDER BY created_at DESC, id DESC
    LIMIT ?
  `);
  const listInstallStateStatement = db.prepare(`
    SELECT *
    FROM install_state
    ORDER BY installed_at DESC, target_id ASC
  `);
  const countPendingGovernanceStatement = db.prepare(`
    SELECT COUNT(*) AS total_count
    FROM governance_events
    WHERE resolved_at IS NULL
  `);
  const listPendingGovernanceStatement = db.prepare(`
    SELECT *
    FROM governance_events
    WHERE resolved_at IS NULL
    ORDER BY created_at DESC, id DESC
    LIMIT ?
  `);
  const getSkillVersionStatement = db.prepare(`
    SELECT *
    FROM skill_versions
    WHERE skill_id = ? AND version = ?
  `);

  const upsertSessionStatement = db.prepare(`
    INSERT INTO sessions (
      id,
      adapter_id,
      harness,
      state,
      repo_root,
      started_at,
      ended_at,
      snapshot
    ) VALUES (
      @id,
      @adapter_id,
      @harness,
      @state,
      @repo_root,
      @started_at,
      @ended_at,
      @snapshot
    )
    ON CONFLICT(id) DO UPDATE SET
      adapter_id = excluded.adapter_id,
      harness = excluded.harness,
      state = excluded.state,
      repo_root = excluded.repo_root,
      started_at = excluded.started_at,
      ended_at = excluded.ended_at,
      snapshot = excluded.snapshot
  `);

  const insertSkillRunStatement = db.prepare(`
    INSERT INTO skill_runs (
      id,
      skill_id,
      skill_version,
      session_id,
      task_description,
      outcome,
      failure_reason,
      tokens_used,
      duration_ms,
      user_feedback,
      created_at
    ) VALUES (
      @id,
      @skill_id,
      @skill_version,
      @session_id,
      @task_description,
      @outcome,
      @failure_reason,
      @tokens_used,
      @duration_ms,
      @user_feedback,
      @created_at
    )
    ON CONFLICT(id) DO UPDATE SET
      skill_id = excluded.skill_id,
      skill_version = excluded.skill_version,
      session_id = excluded.session_id,
      task_description = excluded.task_description,
      outcome = excluded.outcome,
      failure_reason = excluded.failure_reason,
      tokens_used = excluded.tokens_used,
      duration_ms = excluded.duration_ms,
      user_feedback = excluded.user_feedback,
      created_at = excluded.created_at
  `);

  const upsertSkillVersionStatement = db.prepare(`
    INSERT INTO skill_versions (
      skill_id,
      version,
      content_hash,
      amendment_reason,
      promoted_at,
      rolled_back_at
    ) VALUES (
      @skill_id,
      @version,
      @content_hash,
      @amendment_reason,
      @promoted_at,
      @rolled_back_at
    )
    ON CONFLICT(skill_id, version) DO UPDATE SET
      content_hash = excluded.content_hash,
      amendment_reason = excluded.amendment_reason,
      promoted_at = excluded.promoted_at,
      rolled_back_at = excluded.rolled_back_at
  `);

  const insertDecisionStatement = db.prepare(`
    INSERT INTO decisions (
      id,
      session_id,
      title,
      rationale,
      alternatives,
      supersedes,
      status,
      created_at
    ) VALUES (
      @id,
      @session_id,
      @title,
      @rationale,
      @alternatives,
      @supersedes,
      @status,
      @created_at
    )
    ON CONFLICT(id) DO UPDATE SET
      session_id = excluded.session_id,
      title = excluded.title,
      rationale = excluded.rationale,
      alternatives = excluded.alternatives,
      supersedes = excluded.supersedes,
      status = excluded.status,
      created_at = excluded.created_at
  `);

  const upsertInstallStateStatement = db.prepare(`
    INSERT INTO install_state (
      target_id,
      target_root,
      profile,
      modules,
      operations,
      installed_at,
      source_version
    ) VALUES (
      @target_id,
      @target_root,
      @profile,
      @modules,
      @operations,
      @installed_at,
      @source_version
    )
    ON CONFLICT(target_id, target_root) DO UPDATE SET
      profile = excluded.profile,
      modules = excluded.modules,
      operations = excluded.operations,
      installed_at = excluded.installed_at,
      source_version = excluded.source_version
  `);

  const insertGovernanceEventStatement = db.prepare(`
    INSERT INTO governance_events (
      id,
      session_id,
      event_type,
      payload,
      resolved_at,
      resolution,
      created_at
    ) VALUES (
      @id,
      @session_id,
      @event_type,
      @payload,
      @resolved_at,
      @resolution,
      @created_at
    )
    ON CONFLICT(id) DO UPDATE SET
      session_id = excluded.session_id,
      event_type = excluded.event_type,
      payload = excluded.payload,
      resolved_at = excluded.resolved_at,
      resolution = excluded.resolution,
      created_at = excluded.created_at
  `);

  function getSessionById(id) {
    const row = getSessionStatement.get(id);
    return row ? mapSessionRow(row) : null;
  }

  function listRecentSessions(options = {}) {
    const limit = normalizeLimit(options.limit, 10);
    return {
      totalCount: countSessionsStatement.get().total_count,
      sessions: listRecentSessionsStatement.all(limit).map(mapSessionRow),
    };
  }

  function getSessionDetail(id) {
    const session = getSessionById(id);
    if (!session) {
      return null;
    }

    const workers = Array.isArray(session.snapshot && session.snapshot.workers)
      ? session.snapshot.workers.map(worker => ({ ...worker }))
      : [];

    return {
      session,
      workers,
      skillRuns: getSessionSkillRunsStatement.all(id).map(mapSkillRunRow),
      decisions: getSessionDecisionsStatement.all(id).map(mapDecisionRow),
    };
  }

  function getStatus(options = {}) {
    const activeLimit = normalizeLimit(options.activeLimit, 5);
    const recentSkillRunLimit = normalizeLimit(options.recentSkillRunLimit, 20);
    const pendingLimit = normalizeLimit(options.pendingLimit, 5);

    const activeSessions = listActiveSessionsStatement.all(activeLimit).map(mapSessionRow);
    const recentSkillRuns = listRecentSkillRunsStatement.all(recentSkillRunLimit).map(mapSkillRunRow);
    const installations = listInstallStateStatement.all().map(mapInstallStateRow);
    const pendingGovernanceEvents = listPendingGovernanceStatement.all(pendingLimit).map(mapGovernanceEventRow);

    return {
      generatedAt: new Date().toISOString(),
      activeSessions: {
        activeCount: countActiveSessionsStatement.get().total_count,
        sessions: activeSessions,
      },
      skillRuns: {
        windowSize: recentSkillRunLimit,
        summary: summarizeSkillRuns(recentSkillRuns),
        recent: recentSkillRuns,
      },
      installHealth: summarizeInstallHealth(installations),
      governance: {
        pendingCount: countPendingGovernanceStatement.get().total_count,
        events: pendingGovernanceEvents,
      },
    };
  }

  return {
    getSessionById,
    getSessionDetail,
    getStatus,
    insertDecision(decision) {
      const normalized = normalizeDecisionInput(decision);
      assertValidEntity('decision', normalized);
      insertDecisionStatement.run({
        id: normalized.id,
        session_id: normalized.sessionId,
        title: normalized.title,
        rationale: normalized.rationale,
        alternatives: stringifyJson(normalized.alternatives, 'decision.alternatives'),
        supersedes: normalized.supersedes,
        status: normalized.status,
        created_at: normalized.createdAt,
      });
      return normalized;
    },
    insertGovernanceEvent(governanceEvent) {
      const normalized = normalizeGovernanceEventInput(governanceEvent);
      assertValidEntity('governanceEvent', normalized);
      insertGovernanceEventStatement.run({
        id: normalized.id,
        session_id: normalized.sessionId,
        event_type: normalized.eventType,
        payload: stringifyJson(normalized.payload, 'governanceEvent.payload'),
        resolved_at: normalized.resolvedAt,
        resolution: normalized.resolution,
        created_at: normalized.createdAt,
      });
      return normalized;
    },
    insertSkillRun(skillRun) {
      const normalized = normalizeSkillRunInput(skillRun);
      assertValidEntity('skillRun', normalized);
      insertSkillRunStatement.run({
        id: normalized.id,
        skill_id: normalized.skillId,
        skill_version: normalized.skillVersion,
        session_id: normalized.sessionId,
        task_description: normalized.taskDescription,
        outcome: normalized.outcome,
        failure_reason: normalized.failureReason,
        tokens_used: normalized.tokensUsed,
        duration_ms: normalized.durationMs,
        user_feedback: normalized.userFeedback,
        created_at: normalized.createdAt,
      });
      return normalized;
    },
    listRecentSessions,
    upsertInstallState(installState) {
      const normalized = normalizeInstallStateInput(installState);
      assertValidEntity('installState', normalized);
      upsertInstallStateStatement.run({
        target_id: normalized.targetId,
        target_root: normalized.targetRoot,
        profile: normalized.profile,
        modules: stringifyJson(normalized.modules, 'installState.modules'),
        operations: stringifyJson(normalized.operations, 'installState.operations'),
        installed_at: normalized.installedAt,
        source_version: normalized.sourceVersion,
      });
      return normalized;
    },
    upsertSession(session) {
      const normalized = normalizeSessionInput(session);
      assertValidEntity('session', normalized);
      upsertSessionStatement.run({
        id: normalized.id,
        adapter_id: normalized.adapterId,
        harness: normalized.harness,
        state: normalized.state,
        repo_root: normalized.repoRoot,
        started_at: normalized.startedAt,
        ended_at: normalized.endedAt,
        snapshot: stringifyJson(normalized.snapshot, 'session.snapshot'),
      });
      return getSessionById(normalized.id);
    },
    upsertSkillVersion(skillVersion) {
      const normalized = normalizeSkillVersionInput(skillVersion);
      assertValidEntity('skillVersion', normalized);
      upsertSkillVersionStatement.run({
        skill_id: normalized.skillId,
        version: normalized.version,
        content_hash: normalized.contentHash,
        amendment_reason: normalized.amendmentReason,
        promoted_at: normalized.promotedAt,
        rolled_back_at: normalized.rolledBackAt,
      });
      const row = getSkillVersionStatement.get(normalized.skillId, normalized.version);
      return row ? mapSkillVersionRow(row) : null;
    },
  };
}

module.exports = {
  ACTIVE_SESSION_STATES,
  FAILURE_OUTCOMES,
  SUCCESS_OUTCOMES,
  createQueryApi,
};