import { afterEach, beforeEach, expect, it, vi } from 'vitest';
import { newFixture, type Fixture } from '../helpers/fixture.js';
let fixture: Fixture;
beforeEach(async () => { vi.resetModules(); fixture = await newFixture(['t5_test']); });
afterEach(async () => { await fixture.cleanup(); });

it('counts rebuilds once across pools and keeps their capacity through migration handoff and lower limits', async () => {
    const { db } = await import('../../src/lib/server/db/index.js');
    const { fleetSettings, saveFleetSettings } = await import('../../src/lib/server/settings.js');
    const { concurrencyBlocker, lifecycleHolders, preparingJobs } = await import('../../src/lib/server/provisioning/concurrency.js');
    const h = db();
    h.prepare("INSERT INTO native_instances(id,server,host_id,generation,library_id,image,port,created_at) VALUES('i','t5_test','source',1,'lib','img',1,'2026-01-01')").run();
    h.prepare("INSERT INTO server_deployments(id,server,action,state,stage,started_at,triggered_by) VALUES('a','t5_test','rebuild','waiting','migrating','2026-01-01','test')").run();
    h.prepare("INSERT INTO native_provisioning(deployment_id,instance_id,generation) VALUES('a','i',1)").run();
    h.prepare("INSERT INTO ec_host_migrations(deployment_id,source_host_id,instance_id,target_host_id,remove_operation_id,removed_at) VALUES('a','source','i','target','remove','2026-01-02')").run();
    saveFleetSettings({ ...fleetSettings(), lifecycleConcurrency: 1, rebuildConcurrency: 1 });
    expect(lifecycleHolders()).toHaveLength(1);
    expect(concurrencyBlocker('b','stop','other')).toContain('lifecycle');
    expect(concurrencyBlocker('a','rebuild','target')).toBeNull();
    saveFleetSettings({ ...fleetSettings(), lifecycleConcurrency: 0 });
    expect(concurrencyBlocker('b','rebuild','other')).toContain('rebuild');
    saveFleetSettings({ ...fleetSettings(), rebuildConcurrency: 0, createConcurrencyPerHost: 1 });
    expect(concurrencyBlocker('b','create','target')).toContain('startup');
    expect(concurrencyBlocker('b','create','other')).toBeNull();
    preparingJobs.add('a');
    expect(lifecycleHolders()).toHaveLength(1);
    preparingJobs.clear();
});

it('enforces per-host removal and recovery limits independently of other hosts', async () => {
    const { db } = await import('../../src/lib/server/db/index.js');
    const { fleetSettings, saveFleetSettings } = await import('../../src/lib/server/settings.js');
    const { concurrencyBlocker } = await import('../../src/lib/server/provisioning/concurrency.js');
    const h = db();
    h.prepare("INSERT INTO servers(name) VALUES('t5_test')").run();
    h.prepare("INSERT INTO native_instances(id,server,host_id,generation,library_id,image,port,created_at) VALUES('i','t5_test','host',1,'lib','img',1,'2026-01-01')").run();
    h.prepare("INSERT INTO server_deployments(id,server,action,state,stage,started_at,triggered_by) VALUES('a','t5_test','destroy','running','removing','2026-01-01','test')").run();
    h.prepare("INSERT INTO native_provisioning(deployment_id,instance_id,generation) VALUES('a','i',1)").run();
    saveFleetSettings({ ...fleetSettings(), destroyConcurrencyPerHost: 1, restartConcurrencyPerHost: 1 });
    expect(concurrencyBlocker('b','destroy','host')).toContain('destruction');
    expect(concurrencyBlocker('b','destroy','other')).toBeNull();
    h.prepare("INSERT INTO restart_rollout(server,requested_at,operation_id) VALUES('t5_test','2026-01-01','a')").run();
    expect(concurrencyBlocker('b','restart','host')).toContain('recovery');
    expect(concurrencyBlocker('b','restart','other')).toBeNull();
});

it('counts a creation recovery rebuild against rebuild capacity without losing its startup reservation', async () => {
    const { db } = await import('../../src/lib/server/db/index.js');
    const { fleetSettings, saveFleetSettings } = await import('../../src/lib/server/settings.js');
    const { concurrencyBlocker, lifecycleHolders } = await import('../../src/lib/server/provisioning/concurrency.js');
    db().prepare("INSERT INTO native_instances(id,server,host_id,library_id,image,port,created_at) VALUES('i','t5_test','host','lib','img',1,'2026-01-01')").run();
    db().prepare("INSERT INTO server_deployments(id,server,action,state,stage,started_at,triggered_by) VALUES('a','t5_test','create','running','recovery','2026-01-01','test')").run();
    db().prepare("INSERT INTO native_provisioning(deployment_id,instance_id,generation,recovery_step) VALUES('a','i',1,'rebuild')").run();
    saveFleetSettings({ ...fleetSettings(), rebuildConcurrency: 1, createConcurrencyPerHost: 1 });
    expect(lifecycleHolders()).toEqual([expect.objectContaining({ id: 'a', action: 'rebuild' })]);
    expect(concurrencyBlocker('b', 'rebuild', 'other')).toContain('rebuild');
    expect(concurrencyBlocker('b', 'create', 'host')).toContain('startup');
    expect(concurrencyBlocker('a', 'rebuild', 'host')).toBeNull();
});

it('retains every capacity owner across failure, cancellation and migration without counting completed history', async () => {
    const { db } = await import('../../src/lib/server/db/index.js');
    const { createHost } = await import('../../src/lib/server/hosts/index.js');
    const { lifecycleHolders, preparingJobs } = await import('../../src/lib/server/provisioning/concurrency.js');
    const h = db(), host = createHost({name:'Source'});
    const add = (id: string, state: string, command?: string, migration = false) => {
        h.prepare("INSERT INTO server_deployments(id,server,action,state,stage,started_at,triggered_by) VALUES(?,?,'rebuild',?,'test','2026-01-01','test')").run(id,id,state);
        h.prepare("INSERT INTO native_instances(id,server,host_id,library_id,image,port,created_at) VALUES(?,?,?,'lib','img',1,'2026-01-01')").run(id,id,host.id);
        h.prepare('INSERT INTO native_provisioning(deployment_id,instance_id,generation,operation_id) VALUES(?,?,1,?)').run(id,id,migration ? null : command ? id : null);
        if (command) h.prepare("INSERT INTO ec_host_operations(id,host_id,kind,state,payload,created_at,updated_at) VALUES(?,?,'instance.rebuild',?,'{}','2026-01-01','2026-01-01')").run(id,host.id,command);
        if (migration) h.prepare('INSERT INTO ec_host_migrations(deployment_id,source_host_id,instance_id,target_host_id,remove_operation_id) VALUES(?,?,?,?,?)').run(id,host.id,id,'target',command ? id : null);
    };
    add('running','running','running');
    add('health','awaiting-health','completed');
    add('prepared','queued');
    add('recovery','failed','failed');
    add('cancelled-command','cancelled','unknown');
    add('done-command','done','pending');
    add('failed-migration','failed','completed',true);
    add('unknown-migration','legacy-unknown','completed',true);
    add('cancelled-migration','cancelled','accepted',true);
    add('waiting-migration','waiting','running',true);
    add('finished','done','completed');
    add('cancelled-finished','cancelled','completed',true);
    add('finished-migration','warning','completed',true);
    add('queued','queued');
    h.prepare("INSERT INTO servers(name) VALUES('recovery')").run();
    h.prepare("INSERT INTO restart_rollout(server,operation_id,requested_at) VALUES('recovery','recovery','2026-01-01')").run();
    preparingJobs.add('prepared');
    try {
        const holders = lifecycleHolders();
        expect(holders.map(row=>row.id).sort()).toEqual(['running','health','prepared','recovery','cancelled-command','done-command','failed-migration','unknown-migration','cancelled-migration','waiting-migration'].sort());
        expect(holders.find(row=>row.id==='waiting-migration')).toMatchObject({host_id:host.id,target_host_id:'target',removing:1});
    } finally { preparingJobs.clear(); }
});

it('seeks capacity owners through active indexes instead of scanning retained jobs and receipts', async () => {
    const { db } = await import('../../src/lib/server/db/index.js');
    const { createHost } = await import('../../src/lib/server/hosts/index.js');
    const { lifecycleHolders } = await import('../../src/lib/server/provisioning/concurrency.js');
    const h = db(), host = createHost({name:'History host'});
    h.transaction(() => {
        const job = h.prepare("INSERT INTO server_deployments(id,server,action,state,stage,started_at,triggered_by) VALUES(?,'old','restart','done','Done','2026-01-01','test')");
        const operation = h.prepare("INSERT INTO ec_host_operations(id,host_id,kind,state,payload,created_at,updated_at) VALUES(?,?,'instance.restart','completed','{}','2026-01-01','2026-01-01')");
        h.prepare("INSERT INTO native_instances(id,server,host_id,library_id,image,port,created_at) VALUES('i','old',?,'lib','img',1,'2026-01-01')").run(host.id);
        const native = h.prepare("INSERT INTO native_provisioning(deployment_id,instance_id,generation,operation_id) VALUES(?,'i',1,?)");
        const migration = h.prepare("INSERT INTO ec_host_migrations(deployment_id,source_host_id,instance_id,remove_operation_id,removed_at) VALUES(?,?,'i',?,'2026-01-01')");
        for (let n=0;n<4000;n++) {
            const id=String(n); job.run(id); operation.run(id,host.id); native.run(id,id); migration.run(id,host.id,id);
        }
    })();
    const prepare = vi.spyOn(h,'prepare');
    let sql: string;
    try {
        expect(lifecycleHolders()).toEqual([]);
        sql = prepare.mock.calls.find(([sql])=>sql.startsWith('SELECT d.id,'))![0];
    } finally { prepare.mockRestore(); }
    const plan = h.prepare(`EXPLAIN QUERY PLAN ${sql}`).all('[]') as {detail:string}[];
    const details = plan.map(row=>row.detail).join('\n');
    for (const index of ['idx_server_deployments_state','idx_server_deployments_unsettled','ec_host_operations_active','native_provisioning_operation','ec_host_migrations_operation']) {
        expect(details).toContain(index);
    }
    expect(details).not.toMatch(/SCAN (?:d|n|m|o)\b/);
    // Scanning the small partial index of unsettled IDs is intentional.
    expect(details).not.toMatch(/SCAN server_deployments(?! USING INDEX idx_server_deployments_unsettled)\b/);
});