package api

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"git.misaka.ren/m1saka/dsh-web/internal/store"
	"io"
	"net/http"
	"net/url"
	"regexp"
	"strings"
	"sync"
	"time"
)

// Caller holds buildQueue; interrupted jobs cannot be reported as successful.
func (a *API) ensureBuilds() error {
	if buildQueue.initialized[a.s.DB] {
		return nil
	}
	_, err := a.s.DB.Exec(`CREATE TABLE IF NOT EXISTS image_builds(id TEXT PRIMARY KEY,version TEXT NOT NULL,status TEXT NOT NULL,logs TEXT NOT NULL DEFAULT '',error TEXT NOT NULL DEFAULT '',image_id TEXT NOT NULL DEFAULT '',created_at TEXT NOT NULL); CREATE TABLE IF NOT EXISTS image_build_requests(user_id TEXT NOT NULL,build_id TEXT PRIMARY KEY,created_at TEXT NOT NULL); CREATE TABLE IF NOT EXISTS images(image_id TEXT PRIMARY KEY,version TEXT NOT NULL,recipe_rev TEXT,platform TEXT,tag TEXT NOT NULL DEFAULT '',status TEXT NOT NULL,built_at TEXT NOT NULL,usage_count INTEGER NOT NULL DEFAULT 0);`)
	if err != nil {
		return err
	}
	for _, q := range []string{
		"CREATE INDEX IF NOT EXISTS image_builds_history ON image_builds(created_at DESC,id DESC)",
		"ALTER TABLE image_builds ADD COLUMN requested_by TEXT NOT NULL DEFAULT ''",
		"ALTER TABLE image_builds ADD COLUMN recipe_rev TEXT",
		"ALTER TABLE image_builds ADD COLUMN platform TEXT",
		"ALTER TABLE image_builds ADD COLUMN finished_at TEXT",
		"ALTER TABLE image_builds ADD COLUMN experimental INTEGER NOT NULL DEFAULT 0",
		"ALTER TABLE image_builds ADD COLUMN release_id TEXT NOT NULL DEFAULT ''",
		"ALTER TABLE image_builds ADD COLUMN source_repository TEXT NOT NULL DEFAULT ''",
		"ALTER TABLE image_builds ADD COLUMN source_commit TEXT NOT NULL DEFAULT ''",
		"CREATE TABLE IF NOT EXISTS image_admissions(image_id TEXT NOT NULL,version TEXT NOT NULL,recipe_rev TEXT NOT NULL,platform TEXT NOT NULL,state TEXT NOT NULL,evidence TEXT NOT NULL,admitted_by TEXT NOT NULL,admitted_at TEXT NOT NULL,PRIMARY KEY(image_id,version,recipe_rev,platform))",
		"ALTER TABLE images ADD COLUMN recipe_rev TEXT",
		"ALTER TABLE images ADD COLUMN platform TEXT",
		"ALTER TABLE images ADD COLUMN usage_count INTEGER NOT NULL DEFAULT 0",
	} {
		if _, e := a.s.DB.Exec(q); e != nil && !strings.Contains(strings.ToLower(e.Error()), "duplicate column") {
			return e
		}
	}
	_, err = a.s.DB.Exec("DROP INDEX IF EXISTS image_builds_version; DROP INDEX IF EXISTS image_builds_identity; CREATE UNIQUE INDEX image_builds_identity ON image_builds(version,recipe_rev,platform) WHERE release_id='' AND recipe_rev IS NOT NULL AND platform IS NOT NULL AND status IN ('queued','running','validating','success'); CREATE UNIQUE INDEX IF NOT EXISTS image_builds_release_identity ON image_builds(source_repository,source_commit,release_id,platform) WHERE release_id<>'' AND status IN ('queued','running','validating','success')")
	if err != nil {
		return err
	}
	if !buildQueue.initialized[a.s.DB] {
		if _, err = a.s.DB.Exec("UPDATE image_builds SET status='failed',error='image template identity is unknown' WHERE status='queued' AND (recipe_rev IS NULL OR recipe_rev<>? OR platform IS NULL OR platform<>?)", imageRecipeRev, imagePlatform); err != nil {
			return err
		}
		if _, err = a.s.DB.Exec("UPDATE image_builds SET status='failed',error='build interrupted by process restart' WHERE status IN ('running','validating')"); err != nil {
			return err
		}
		buildQueue.initialized[a.s.DB] = true
	}
	return nil
}
func (a *API) builds(w http.ResponseWriter, r *http.Request) {
	_, _, authErr := a.user(r)
	if authErr != nil {
		fail(w, 401, "authentication required")
		return
	}
	if r.Method != http.MethodGet {
		fail(w, 405, "method not allowed")
		return
	}
	a.listBuilds(w, r)
}

var errBuildRateLimited = errors.New("build limit: three new tasks per user per hour")

func (a *API) startBuildWorker() {
	buildQueue.Lock()
	defer buildQueue.Unlock()
	a.startBuildWorkerLocked()
}

// startBuildWorkerLocked requires the caller to hold buildQueue: the active map
// is only safe under that lock.
func (a *API) startBuildWorkerLocked() {
	if buildQueue.active[a.s.DB] {
		return
	}
	buildQueue.active[a.s.DB] = true
	go func() {
		var lastCleanupAudit time.Time
		var nextCleanup time.Time
		var recoveryErr error
		for {
			select {
			case <-a.s.Done():
				buildQueue.Lock()
				delete(buildQueue.active, a.s.DB)
				buildQueue.Unlock()
				return
			default:
			}
			if time.Now().After(nextCleanup) {
				buildWorker.Lock()
				recovery, cancel := context.WithTimeout(context.Background(), 20*time.Second)
				recoveryErr = a.recoverBuildChecks(recovery)
				cancel()
				buildWorker.Unlock()
				if errors.Is(recoveryErr, errBuildCheckUncertain) {
					nextCleanup = time.Now().Add(time.Minute)
				}
			}
			if recoveryErr != nil {
				if time.Since(lastCleanupAudit) >= time.Minute {
					a.s.AddAudit("", "build.cleanup_error", "", sanitizeBuildLog(recoveryErr.Error()))
					lastCleanupAudit = time.Now()
				}
			}
			buildQueue.Lock()
			var b buildRecord
			row := a.s.DB.QueryRow("SELECT " + buildSummaryColumns + " FROM image_builds WHERE status='queued' AND release_id<>'' ORDER BY created_at,id LIMIT 1")
			err := scanBuildSummary(row, &b)
			if err == nil {
				_, err = a.s.DB.Exec("UPDATE image_builds SET status='running' WHERE id=?", b.ID)
			}
			if err != nil {
				if !errors.Is(err, sql.ErrNoRows) || recoveryErr != nil {
					buildQueue.Unlock()
					select {
					case <-a.s.Done():
					case <-time.After(time.Second):
					}
					continue
				}
				delete(buildQueue.active, a.s.DB)
				buildQueue.Unlock()
				return
			}
			buildQueue.Unlock()
			a.runImageBuild(b)
			nextCleanup = time.Time{}
		}
	}()
}
func (a *API) runImageBuild(b buildRecord) {
	buildWorker.Lock()
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Minute)
	defer cancel()
	logs := ""
	rawLogs := ""
	var logErr error
	appendLog := func(s string) {
		if len(rawLogs) < buildLogLimit {
			remaining := buildLogLimit - len(rawLogs)
			if len(s) > remaining {
				s = s[:remaining]
			}
			rawLogs += s
		}
		logs = sanitizeBuildLog(rawLogs)
		if logErr == nil {
			_, logErr = a.s.DB.Exec("UPDATE image_builds SET logs=? WHERE id=?", logs, b.ID)
		}
	}
	var id string
	var err error
	if b.ReleaseID == "" {
		err = errors.New("Git release identity required")
	} else {
		var tarball io.Reader
		tarball, err = a.releaseBuildContext(ctx, b)
		if err == nil {
			err = a.checkBuildDisk(ctx)
		}
		if err == nil {
			id, err = a.docker.BuildRelease(ctx, tarball, b.Version, "dsh-web:release-"+b.SourceCommit, b.ReleaseID, b.SourceRepository, b.SourceCommit, appendLog)
		}
	}
	if err == nil {
		var matches bool
		matches, err = a.buildImageMatches(ctx, id, b)
		if err == nil && !matches {
			err = errors.New("image template or platform mismatch")
		}
	}
	if err == nil {
		_, err = a.s.DB.Exec("UPDATE image_builds SET status='validating',image_id=? WHERE id=?", id, b.ID)
	}
	if err == nil {
		err = a.verifyBuiltImage(ctx, id, b.Version, b.ID)
	}
	if err == nil {
		err = logErr
	}
	status, detail := "success", ""
	if err != nil {
		status = "failed"
		detail = sanitizeBuildLog(err.Error())
		appendLog(string(rune(10)) + detail)
	}
	finished := time.Now().UTC().Format(time.RFC3339Nano)
	buildWorker.Unlock()
	if err := a.persistBuildResult(b, status, logs, detail, id, finished); err != nil {
		go a.finishBuild(b, status, logs, detail, id, finished)
	}
}
func (a *API) verifyBuiltImage(parent context.Context, image, version string, buildIDs ...string) (result error) {
	ctx, cancel := context.WithTimeout(parent, 90*time.Second)
	defer cancel()
	id := store.ID()
	if len(buildIDs) != 0 {
		id = buildIDs[0]
	}
	if err := a.ensureBuildChecks(); err != nil {
		return err
	}
	if _, err := a.s.DB.Exec("INSERT INTO image_build_checks(build_id,image_id,created_at) VALUES(?,?,?)", id, image, time.Now().UTC().Format(time.RFC3339Nano)); err != nil {
		return err
	}
	var created struct {
		ID string `json:"Id"`
	}
	rejected := false
	defer func() {
		cleanup, c := context.WithTimeout(context.Background(), 10*time.Second)
		defer c()
		var err error
		if rejected {
			_, err = a.s.DB.Exec("DELETE FROM image_build_checks WHERE build_id=?", id)
		} else if created.ID != "" {
			err = a.deleteBuildCheck(cleanup, id, created.ID)
		} else {
			err = a.cleanupBuildCheck(cleanup, id, image)
		}
		result = errors.Join(result, err)
	}()
	config := map[string]any{"Image": image, "User": "1000:1000", "Labels": map[string]string{"dsh-mgr.role": "build-check", "dsh-mgr.build": id}, "HostConfig": map[string]any{"NetworkMode": "none", "ReadonlyRootfs": true, "CapDrop": []string{"ALL"}, "SecurityOpt": []string{"no-new-privileges:true"}, "Memory": int64(1 << 30), "NanoCpus": int64(1e9), "PidsLimit": 256, "Tmpfs": map[string]string{"/tmp": "rw,exec,nosuid,nodev,size=256m,mode=1777", "/workspace": "rw,nosuid,nodev,size=256m,uid=1000,gid=1000"}}}
	if err := a.docker.Do(ctx, http.MethodPost, "/containers/create?name="+url.QueryEscape(buildCheckName(id)), config, &created); err != nil {
		rejected = dockerCreateRejected(err)
		return err
	}
	if created.ID == "" {
		return errors.New("verification container ID missing")
	}
	if _, err := a.s.DB.Exec("UPDATE image_build_checks SET container_id=? WHERE build_id=?", created.ID, id); err != nil {
		return err
	}
	path := "/containers/" + url.PathEscape(created.ID)
	if err := a.docker.Do(ctx, http.MethodPost, path+"/start", nil, nil); err != nil {
		return err
	}
	script := `const end=Date.now()+60000;async function probe(){try{const r=await fetch('http://127.0.0.1:8080/',{redirect:'manual',signal:AbortSignal.timeout(2000)});if(r.status>=200&&r.status<500)process.exit(0);}catch{}if(Date.now()>end)process.exit(1);setTimeout(probe,500);}probe();`
	{
		expected, _ := json.Marshal(version)
		script = `const cp=require('node:child_process');const actual=cp.execFileSync('dsh',['--version'],{encoding:'utf8',timeout:20000}).trim();if(actual!==` + string(expected) + `)process.exit(2);` + script
	}
	script = `const fs=require('node:fs');for(const [k,v] of Object.entries({DSH_HOME:'/workspace',HOME:'/workspace',XDG_DATA_HOME:'/workspace/.local/share',XDG_CONFIG_HOME:'/workspace/.config'})){if(process.env[k]!==v)process.exit(3);}if(!fs.lstatSync('/data/dsh-home').isSymbolicLink()||fs.realpathSync('/data/dsh-home')!=='/workspace')process.exit(4);fs.writeFileSync('/workspace/.home-check','isolated');if(fs.readFileSync('/data/dsh-home/.home-check','utf8')!=='isolated')process.exit(5);fs.unlinkSync('/workspace/.home-check');` + script
	var exec struct {
		ID string `json:"Id"`
	}
	if err := a.docker.Do(ctx, http.MethodPost, path+"/exec", map[string]any{"Cmd": []string{"node", "-e", script}, "User": "1000:1000"}, &exec); err != nil {
		return err
	}
	if exec.ID == "" {
		return errors.New("verification exec ID missing")
	}
	ep := "/exec/" + url.PathEscape(exec.ID)
	if err := a.docker.Do(ctx, http.MethodPost, ep+"/start", map[string]bool{"Detach": true, "Tty": false}, nil); err != nil {
		return err
	}
	ticker := time.NewTicker(250 * time.Millisecond)
	defer ticker.Stop()
	for {
		var state struct {
			Running  bool
			ExitCode int
		}
		if err := a.docker.Do(ctx, http.MethodGet, ep+"/json", nil, &state); err != nil {
			return err
		}
		if !state.Running {
			if state.ExitCode != 0 {
				return fmt.Errorf("image startup verification failed (exit %d)", state.ExitCode)
			}
			container, err := a.docker.Inspect(ctx, created.ID)
			if err != nil {
				return err
			}
			if !container.State.Running {
				return errors.New("verification container exited")
			}
			return nil
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-ticker.C:
		}
	}
}

const buildLogLimit = 64 << 10

var fixedVersion = regexp.MustCompile(`^(0|[1-9][0-9]*)[.](0|[1-9][0-9]*)[.](0|[1-9][0-9]*)(-[0-9A-Za-z-]+([.][0-9A-Za-z-]+)*)?$`)
var buildSecrets = regexp.MustCompile(`(?i)(authorization["']?[[:space:]]*[:=][[:space:]]*["']?(?:bearer[[:space:]]+|basic[[:space:]]+)?|(?:token|password|passwd|secret|api[_-]?key|cookie)["']?[[:space:]]*[:=][[:space:]]*["']?)[^[:space:]"'&,;]+`)
var buildURLCredentials = regexp.MustCompile(`(https?://)[^/@[:space:]]+:[^/@[:space:]]+@`)
var buildQueue = struct {
	sync.Mutex
	initialized map[*sql.DB]bool
	active      map[*sql.DB]bool
}{initialized: map[*sql.DB]bool{}, active: map[*sql.DB]bool{}}
var buildWorker sync.Mutex

type imageRecord struct {
	Admission       string `json:"admission"`
	AdmissionReason string `json:"admission_reason"`
	Selectable      bool   `json:"selectable"`
	ID              string `json:"id"`
	ImageID         string `json:"image_id"`
	Version         string `json:"version"`
	Tag             string `json:"tag,omitempty"`
	Status          string `json:"status"`
	Created         string `json:"created_at"`
	RecipeRev       string `json:"recipe_rev,omitempty"`
	Platform        string `json:"platform,omitempty"`
	UsageCount      int    `json:"usage_count"`
}
type buildRecord struct {
	ReleaseID        string `json:"release_id,omitempty"`
	SourceRepository string `json:"source_repository,omitempty"`
	SourceCommit     string `json:"source_commit,omitempty"`
	Experimental     bool   `json:"experimental"`
	ImageID          string `json:"image_id,omitempty"`
	ID               string `json:"id"`
	Version          string `json:"version"`
	Status           string `json:"status"`
	Logs             string `json:"logs,omitempty"`
	Error            string `json:"error,omitempty"`
	Created          string `json:"created_at"`
	RequestedBy      string `json:"requested_by,omitempty"`
	RecipeRev        string `json:"recipe_rev,omitempty"`
	Platform         string `json:"platform,omitempty"`
	Finished         string `json:"finished_at,omitempty"`
}

func (a *API) images(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodDelete {
		a.deleteImage(w, r)
		return
	}
	if _, _, err := a.user(r); err != nil {
		fail(w, 401, "authentication required")
		return
	}
	if r.Method != http.MethodGet {
		fail(w, 405, "method not allowed")
		return
	}
	ctx, cancel := context.WithTimeout(r.Context(), 15*time.Second)
	defer cancel()
	result, err := a.imageIndex(ctx)
	if err != nil {
		fail(w, 502, "image index reconciliation failed")
		return
	}
	writeJSON(w, result)
}

func (a *API) successfulImageIDs(ctx context.Context) ([]string, error) {
	rows, err := a.s.DB.QueryContext(ctx, "SELECT DISTINCT image_id FROM image_builds WHERE status='success' AND image_id<>''")
	if err != nil {
		return nil, err
	}
	ids := []string{}
	for rows.Next() {
		var id string
		if err = rows.Scan(&id); err != nil {
			rows.Close()
			return nil, err
		}
		ids = append(ids, id)
	}
	err = rows.Err()
	rows.Close()
	if err != nil {
		return nil, err
	}
	return ids, nil
}

func (a *API) verifiedImages(ctx context.Context) (map[string]string, error) {
	buildQueue.Lock()
	err := a.ensureBuilds()
	buildQueue.Unlock()
	if err != nil {
		return nil, err
	}
	ids, err := a.successfulImageIDs(ctx)
	if err != nil {
		return nil, err
	}
	result := map[string]string{}
	for _, id := range ids {
		im, err := a.evaluateImage(ctx, id)
		if err != nil {
			return nil, err
		}
		if im.Selectable {
			result[id] = im.Version
		}
	}
	return result, nil
}

func validBuildVersion(v string) bool { return len(v) <= 100 && fixedVersion.MatchString(v) }
func sanitizeBuildLog(s string) string {
	s = buildURLCredentials.ReplaceAllString(s, "$1[REDACTED]@")
	s = buildSecrets.ReplaceAllString(s, "$1[REDACTED]")
	s = strings.ToValidUTF8(s, "")
	if len(s) > buildLogLimit {
		s = strings.ToValidUTF8(s[:buildLogLimit], "")
	}
	return s
}