// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

package coredata

import (
	"context"
	"fmt"
	"maps"
	"time"

	"github.com/getprobo/probo/pkg/gid"
	"github.com/getprobo/probo/pkg/page"
	"github.com/jackc/pgx/v5"

	"go.gearno.de/kit/pg"
)

type (
	Task struct {
		ID           gid.GID       `db:"id"`
		ControlID    gid.GID       `db:"control_id"`
		Name         string        `db:"name"`
		Description  string        `db:"description"`
		State        TaskState     `db:"state"`
		ContentRef   string        `db:"content_ref"`
		CreatedAt    time.Time     `db:"created_at"`
		UpdatedAt    time.Time     `db:"updated_at"`
		Version      int           `db:"version"`
		AssignedTo   *gid.GID      `db:"assigned_to"`
		TimeEstimate time.Duration `db:"time_estimate"`
	}

	Tasks []*Task

	UpdateTaskParams struct {
		ExpectedVersion int
		Name            *string
		Description     *string
		State           *TaskState
		TimeEstimate    *time.Duration
	}
)

func (t Task) CursorKey() page.CursorKey {
	return page.NewCursorKey(t.ID, t.CreatedAt)
}

func (t *Task) LoadByID(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
	taskID gid.GID,
) error {
	q := `
SELECT
    id,
    control_id,
    name,
    description,
	time_estimate,
    state,
	assigned_to,
    content_ref,
    created_at,
    updated_at,
    version
FROM
    tasks
WHERE
    %s
    AND id = @task_id
LIMIT 1;
`

	q = fmt.Sprintf(q, scope.SQLFragment())

	args := pgx.StrictNamedArgs{"task_id": taskID}
	maps.Copy(args, scope.SQLArguments())

	rows, err := conn.Query(ctx, q, args)
	if err != nil {
		return fmt.Errorf("cannot query task: %w", err)
	}

	task, err := pgx.CollectExactlyOneRow(rows, pgx.RowToStructByName[Task])
	if err != nil {
		return fmt.Errorf("cannot collect task: %w", err)
	}

	*t = task

	return nil
}

func (t Task) Insert(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
) error {
	q := `
INSERT INTO tasks (
    tenant_id,
    id,
    name,
    control_id,
    description,
    content_ref,
    created_at,
    updated_at,
    version,
    state,
	time_estimate,
	assigned_to
)
VALUES (
    @tenant_id,
    @task_id,
    @name,
    @control_id,
    @description,
    @content_ref,
    @created_at,
    @updated_at,
    @version,
    @state,
	@time_estimate,
	@assigned_to
);
`

	args := pgx.StrictNamedArgs{
		"tenant_id":     scope.GetTenantID(),
		"task_id":       t.ID,
		"control_id":    t.ControlID,
		"name":          t.Name,
		"description":   t.Description,
		"content_ref":   t.ContentRef,
		"created_at":    t.CreatedAt,
		"updated_at":    t.UpdatedAt,
		"version":       t.Version,
		"state":         t.State,
		"time_estimate": t.TimeEstimate,
		"assigned_to":   t.AssignedTo,
	}
	_, err := conn.Exec(ctx, q, args)
	return err
}

func (t *Tasks) LoadByControlID(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
	controlID gid.GID,
	cursor *page.Cursor,
) error {
	q := `
SELECT
    id,
    control_id,
    name,
    description,
    state,
	time_estimate,
    content_ref,
    created_at,
    updated_at,
    version,
	assigned_to
FROM
    tasks
WHERE
    %s
    AND control_id = @control_id
    AND %s
`

	q = fmt.Sprintf(q, scope.SQLFragment(), cursor.SQLFragment())

	args := pgx.StrictNamedArgs{"control_id": controlID}
	maps.Copy(args, scope.SQLArguments())
	maps.Copy(args, cursor.SQLArguments())

	rows, err := conn.Query(ctx, q, args)
	if err != nil {
		return fmt.Errorf("cannot query tasks: %w", err)
	}

	tasks, err := pgx.CollectRows(rows, pgx.RowToAddrOfStructByName[Task])
	if err != nil {
		return fmt.Errorf("cannot collect tasks: %w", err)
	}

	*t = tasks

	return nil
}

func (t *Task) Update(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
	params UpdateTaskParams,
) error {
	q := `
UPDATE tasks
SET
    name = COALESCE(@name, name),
    description = COALESCE(@description, description),
    state = COALESCE(@state, state),
	time_estimate = COALESCE(@time_estimate, time_estimate),
    updated_at = @updated_at,
    version = version + 1
WHERE
    %s
    AND id = @task_id
    AND version = @expected_version
RETURNING
    version;
`
	q = fmt.Sprintf(q, scope.SQLFragment())

	args := pgx.StrictNamedArgs{
		"task_id":          t.ID,
		"expected_version": params.ExpectedVersion,
		"name":             params.Name,
		"description":      params.Description,
		"state":            params.State,
		"time_estimate":    params.TimeEstimate,
		"updated_at":       time.Now(),
	}
	maps.Copy(args, scope.SQLArguments())

	err := conn.QueryRow(ctx, q, args).Scan(&t.Version)
	return err
}

func (t *Task) AssignTo(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
	assignedTo gid.GID,
) error {
	q := `
UPDATE tasks
SET
    assigned_to = @assigned_to
WHERE
    %s
    AND id = @task_id
`

	q = fmt.Sprintf(q, scope.SQLFragment())

	args := pgx.StrictNamedArgs{
		"task_id":     t.ID,
		"assigned_to": assignedTo,
	}
	maps.Copy(args, scope.SQLArguments())

	_, err := conn.Exec(ctx, q, args)
	return err
}

func (t *Task) Unassign(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
) error {
	q := `
UPDATE tasks
SET
    assigned_to = NULL
WHERE
    %s
    AND id = @task_id
`

	q = fmt.Sprintf(q, scope.SQLFragment())

	args := pgx.StrictNamedArgs{
		"task_id": t.ID,
	}
	maps.Copy(args, scope.SQLArguments())

	_, err := conn.Exec(ctx, q, args)
	return err
}

func (t *Task) Delete(
	ctx context.Context,
	conn pg.Conn,
	scope Scoper,
) error {
	q := `
WITH control_count AS (
    SELECT COUNT(*) AS count FROM controls_tasks WHERE task_id = @task_id
),
delete_link AS (
    DELETE FROM controls_tasks 
    WHERE task_id = @task_id AND control_id = @control_id
    RETURNING task_id
),
delete_transitions AS (
    DELETE FROM task_state_transitions 
    WHERE %s AND task_id = @task_id AND (SELECT count FROM control_count) <= 1
    RETURNING task_id
),
delete_all_links AS (
    DELETE FROM controls_tasks 
    WHERE task_id = @task_id AND (SELECT count FROM control_count) <= 1
    RETURNING task_id
),
delete_task AS (
    DELETE FROM tasks 
    WHERE %s AND id = @task_id AND (SELECT count FROM control_count) <= 1
    RETURNING id
)
SELECT 
    (SELECT count FROM control_count) AS control_count,
    (SELECT COUNT(*) FROM delete_link) AS deleted_links,
    (SELECT COUNT(*) FROM delete_transitions) AS deleted_transitions,
    (SELECT COUNT(*) FROM delete_all_links) AS deleted_all_links,
    (SELECT COUNT(*) FROM delete_task) AS deleted_tasks;
`
	q = fmt.Sprintf(q, scope.SQLFragment(), scope.SQLFragment())

	args := pgx.StrictNamedArgs{
		"task_id":    t.ID,
		"control_id": t.ControlID,
	}
	maps.Copy(args, scope.SQLArguments())

	var controlCount, deletedLinks, deletedTransitions, deletedAllLinks, deletedTasks int
	err := conn.QueryRow(ctx, q, args).Scan(
		&controlCount,
		&deletedLinks,
		&deletedTransitions,
		&deletedAllLinks,
		&deletedTasks,
	)

	if err != nil {
		return fmt.Errorf("cannot execute delete operation: %w", err)
	}

	if controlCount <= 1 {
		if deletedTransitions == 0 || deletedAllLinks == 0 || deletedTasks == 0 {
			return fmt.Errorf("failed to delete task completely: transitions=%d, links=%d, tasks=%d",
				deletedTransitions, deletedAllLinks, deletedTasks)
		}
	} else {
		if deletedLinks == 0 {
			return fmt.Errorf("failed to delete control-task link")
		}
	}

	return nil
}