package infra

import (
	"database/sql"
	"fmt"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"
	"text/tabwriter"

	_ "github.com/mattn/go-sqlite3"
)

// ProjectCoverage reports how well a project registered in registry.db is
// backed by a Gitea sub-repo and how many of its children (apps + analyses)
// are actually cloned on disk. It is the engine of `fn doctor projects`.
//
// The audit only touches the local filesystem and registry.db: it never hits
// the network nor the Gitea API, so it runs fast and requires no token.
type ProjectCoverage struct {
	ProjectID       string   `json:"project_id"`
	DirPath         string   `json:"dir_path"`
	HasGit          bool     `json:"has_git"`          // <root>/<dir_path>/.git exists as a directory
	HasRemote       bool     `json:"has_remote"`       // git -C <dir> remote get-url origin returned a non-empty url
	RepoURLDeclared bool     `json:"repo_url_declared"` // projects.repo_url != ""
	ChildrenInDB    int      `json:"children_in_db"`   // apps + analyses with project_id = ProjectID
	ChildrenCloned  int      `json:"children_cloned"`  // of those, how many have a .git on disk
	ChildrenMissing int      `json:"children_missing"` // ChildrenInDB - ChildrenCloned (at risk when re-cloning)
	Issues          []string `json:"issues"`           // e.g. "dir_not_found", "no_gitea_repo", "children_missing"
}

// AuditProjectsCoverage walks every row in the projects table and reports, per
// project, whether it has a local git repo, whether that repo declares a remote
// origin, whether its repo_url is filled in registry.db, and how many of its
// children (apps + analyses) are cloned versus only known to the database.
//
// registryRoot is the repository root (the directory that holds registry.db).
// All relative dir_path values are resolved against it.
//
// Returns an error only if registry.db cannot be opened or queried. Projects
// whose directory is missing on disk are still reported, flagged with the
// "dir_not_found" issue, so the caller can surface them rather than silently
// dropping them.
func AuditProjectsCoverage(registryRoot string) ([]ProjectCoverage, error) {
	dbPath := filepath.Join(registryRoot, "registry.db")
	dsn := fmt.Sprintf("file:%s?mode=ro&_foreign_keys=on", dbPath)
	db, err := sql.Open("sqlite3", dsn)
	if err != nil {
		return nil, fmt.Errorf("audit_projects_coverage: open db: %w", err)
	}
	defer db.Close()
	if err := db.Ping(); err != nil {
		return nil, fmt.Errorf("audit_projects_coverage: ping db: %w", err)
	}

	rows, err := db.Query(`SELECT id, COALESCE(dir_path,''), COALESCE(repo_url,'') FROM projects ORDER BY id`)
	if err != nil {
		return nil, fmt.Errorf("audit_projects_coverage: query projects: %w", err)
	}
	defer rows.Close()

	var out []ProjectCoverage
	for rows.Next() {
		var pc ProjectCoverage
		var dirPath, repoURL string
		if err := rows.Scan(&pc.ProjectID, &dirPath, &repoURL); err != nil {
			return nil, fmt.Errorf("audit_projects_coverage: scan project: %w", err)
		}

		// DirPath: use projects.dir_path; if empty, derive projects/<id>.
		if dirPath == "" {
			dirPath = filepath.Join("projects", pc.ProjectID)
		}
		pc.DirPath = dirPath
		pc.RepoURLDeclared = repoURL != ""

		absDir := dirPath
		if !filepath.IsAbs(absDir) {
			absDir = filepath.Join(registryRoot, dirPath)
		}

		dirFound := dirExists(absDir)
		if !dirFound {
			pc.Issues = append(pc.Issues, "dir_not_found")
		} else {
			pc.HasGit = dirExists(filepath.Join(absDir, ".git"))
			if pc.HasGit {
				pc.HasRemote = gitHasRemoteOrigin(absDir)
			}
		}

		// Children: apps + analyses with this project_id.
		children, err := projectChildren(db, pc.ProjectID)
		if err != nil {
			return nil, err
		}
		pc.ChildrenInDB = len(children)
		for _, childDir := range children {
			absChild := childDir
			if !filepath.IsAbs(absChild) {
				absChild = filepath.Join(registryRoot, childDir)
			}
			if dirExists(filepath.Join(absChild, ".git")) {
				pc.ChildrenCloned++
			}
		}
		pc.ChildrenMissing = pc.ChildrenInDB - pc.ChildrenCloned

		// Issues derived from the gathered state.
		if !pc.HasRemote && !pc.RepoURLDeclared {
			pc.Issues = append(pc.Issues, "no_gitea_repo")
		}
		if pc.ChildrenMissing > 0 {
			pc.Issues = append(pc.Issues, "children_missing")
		}

		out = append(out, pc)
	}
	return out, rows.Err()
}

// projectChildren returns the dir_path of every app and analysis whose
// project_id matches the given project id.
func projectChildren(db *sql.DB, projectID string) ([]string, error) {
	var dirs []string
	for _, table := range []string{"apps", "analysis"} {
		q := fmt.Sprintf(`SELECT COALESCE(dir_path,'') FROM %s WHERE project_id = ?`, table)
		rows, err := db.Query(q, projectID)
		if err != nil {
			return nil, fmt.Errorf("audit_projects_coverage: query %s children: %w", table, err)
		}
		for rows.Next() {
			var dp string
			if err := rows.Scan(&dp); err != nil {
				rows.Close()
				return nil, fmt.Errorf("audit_projects_coverage: scan %s child: %w", table, err)
			}
			if dp != "" {
				dirs = append(dirs, dp)
			}
		}
		if err := rows.Err(); err != nil {
			rows.Close()
			return nil, err
		}
		rows.Close()
	}
	return dirs, nil
}

// gitHasRemoteOrigin reports whether the git repo at dir declares an origin
// remote with a non-empty URL. It shells out to `git -C <dir> remote get-url
// origin` and treats exit 0 with non-empty output as success. Any error
// (no origin, not a repo, git missing) is reported as false.
func gitHasRemoteOrigin(dir string) bool {
	cmd := exec.Command("git", "-C", dir, "remote", "get-url", "origin")
	outBytes, err := cmd.Output()
	if err != nil {
		return false
	}
	return strings.TrimSpace(string(outBytes)) != ""
}

// FormatProjectsCoverage renders a tabwriter table, one row per project, with
// git / remote / repo_url presence, children cloned vs declared, and the
// issues list. When no project has coverage problems it makes that explicit.
func FormatProjectsCoverage(rows []ProjectCoverage) string {
	var sb strings.Builder
	w := tabwriter.NewWriter(&sb, 0, 0, 2, ' ', 0)
	fmt.Fprintln(w, "PROJECT\tGIT\tREMOTE\tREPO_URL\tCHILDREN\tISSUES")

	withIssues := 0
	for _, r := range rows {
		issues := "-"
		if len(r.Issues) > 0 {
			issues = strings.Join(r.Issues, "; ")
			withIssues++
		}
		fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%d/%d\t%s\n",
			r.ProjectID,
			checkMark(r.HasGit),
			checkMark(r.HasRemote),
			checkMark(r.RepoURLDeclared),
			r.ChildrenCloned, r.ChildrenInDB,
			issues,
		)
	}
	w.Flush()

	if len(rows) == 0 {
		sb.WriteString("\nNo projects registered.\n")
		return sb.String()
	}
	if withIssues == 0 {
		sb.WriteString("\n0 projects con problemas de cobertura.\n")
	} else {
		fmt.Fprintf(&sb, "\n%d/%d projects con problemas de cobertura.\n", withIssues, len(rows))
	}
	return sb.String()
}

// checkMark returns ✓ for true, ✗ for false.
func checkMark(b bool) string {
	if b {
		return "✓"
	}
	return "✗"
}

// OrphanProjectRef describes a project_id that one or more children (apps and
// analyses) reference in registry.db but for which no row exists in the projects
// table. This is the inverse drift of AuditProjectsCoverage: instead of a
// registered project whose children are not cloned, it surfaces an umbrella
// project that was never synced to this PC (or never created here at all), so
// the children are pointing at a project that this registry does not know about.
// That is a data-loss risk: the umbrella project may exist on another machine
// and the link would be silently broken on a clone/sync into this one.
type OrphanProjectRef struct {
	ProjectID string   `json:"project_id"` // referenced by children but missing from projects
	Apps      []string `json:"apps"`       // ids of apps that reference it (sorted)
	Analyses  []string `json:"analyses"`   // ids of analyses that reference it (sorted)
}

// FindOrphanProjectRefs scans every app and analysis that declares a non-empty
// project_id and reports those project_id values that have no matching row in
// the projects table. Each orphan groups the ids of the apps and analyses that
// reference it.
//
// registryRoot is the repository root (the directory that holds registry.db).
//
// The result is sorted by ProjectID, and within each entry the Apps and
// Analyses lists are sorted alphabetically. When every child references a known
// project, an empty (non-nil) slice is returned with a nil error.
//
// Like AuditProjectsCoverage it only reads registry.db (opened read-only) and
// never touches the network nor the Gitea API. Returns an error only when
// registry.db cannot be opened or queried.
func FindOrphanProjectRefs(registryRoot string) ([]OrphanProjectRef, error) {
	dbPath := filepath.Join(registryRoot, "registry.db")
	dsn := fmt.Sprintf("file:%s?mode=ro&_foreign_keys=on", dbPath)
	db, err := sql.Open("sqlite3", dsn)
	if err != nil {
		return nil, fmt.Errorf("find_orphan_project_refs: open db: %w", err)
	}
	defer db.Close()
	if err := db.Ping(); err != nil {
		return nil, fmt.Errorf("find_orphan_project_refs: ping db: %w", err)
	}

	// Set of known project ids.
	known := map[string]bool{}
	prows, err := db.Query(`SELECT id FROM projects`)
	if err != nil {
		return nil, fmt.Errorf("find_orphan_project_refs: query projects: %w", err)
	}
	for prows.Next() {
		var id string
		if err := prows.Scan(&id); err != nil {
			prows.Close()
			return nil, fmt.Errorf("find_orphan_project_refs: scan project: %w", err)
		}
		known[id] = true
	}
	if err := prows.Err(); err != nil {
		prows.Close()
		return nil, err
	}
	prows.Close()

	// Accumulate orphan references from apps and analyses.
	orphans := map[string]*OrphanProjectRef{}

	get := func(pid string) *OrphanProjectRef {
		o, ok := orphans[pid]
		if !ok {
			o = &OrphanProjectRef{ProjectID: pid}
			orphans[pid] = o
		}
		return o
	}

	for _, table := range []string{"apps", "analysis"} {
		q := fmt.Sprintf(`SELECT id, project_id FROM %s WHERE project_id != ''`, table)
		rows, err := db.Query(q)
		if err != nil {
			return nil, fmt.Errorf("find_orphan_project_refs: query %s: %w", table, err)
		}
		for rows.Next() {
			var id, pid string
			if err := rows.Scan(&id, &pid); err != nil {
				rows.Close()
				return nil, fmt.Errorf("find_orphan_project_refs: scan %s row: %w", table, err)
			}
			if known[pid] {
				continue
			}
			o := get(pid)
			if table == "apps" {
				o.Apps = append(o.Apps, id)
			} else {
				o.Analyses = append(o.Analyses, id)
			}
		}
		if err := rows.Err(); err != nil {
			rows.Close()
			return nil, err
		}
		rows.Close()
	}

	out := make([]OrphanProjectRef, 0, len(orphans))
	for _, o := range orphans {
		sort.Strings(o.Apps)
		sort.Strings(o.Analyses)
		out = append(out, *o)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].ProjectID < out[j].ProjectID })
	return out, nil
}

// FormatOrphanProjectRefs renders a human-readable report of orphan project_id
// references, one block per orphan, listing how many apps and analyses point at
// the missing project plus their ids. When there are no orphans it makes that
// explicit on a single line.
func FormatOrphanProjectRefs(rows []OrphanProjectRef) string {
	if len(rows) == 0 {
		return "0 project_id huérfanos (todos los hijos tienen project declarado)\n"
	}

	var sb strings.Builder
	w := tabwriter.NewWriter(&sb, 0, 0, 2, ' ', 0)
	fmt.Fprintln(w, "PROJECT_ID\tAPPS\tANALYSES\tREFERENCED_BY")
	for _, r := range rows {
		refs := append(append([]string{}, r.Apps...), r.Analyses...)
		refStr := strings.Join(refs, ", ")
		if refStr == "" {
			refStr = "-"
		}
		fmt.Fprintf(w, "%s\t%d\t%d\t%s\n",
			r.ProjectID, len(r.Apps), len(r.Analyses), refStr)
	}
	w.Flush()

	fmt.Fprintf(&sb, "\n%d project_id huérfanos (referenciados por hijos pero sin fila en projects).\n", len(rows))
	return sb.String()
}